Future Bitcoin evolutions : covenants, Ark, BitVM

Five years after Taproot×TaprootMajor Bitcoin upgrade activated in November 2021 (BIP 341). Brings more privacy, scripting flexibility and the efficiency of Schnorr signatures.See in the lexicon → (November 2021), Bitcoin has had no new soft-fork×Fork (soft fork, hard fork)Change to the protocol rules. A soft fork stays compatible with old nodes (SegWit, Taproot); a hard fork creates a separate chain (Bitcoin Cash in 2017).See in the lexicon →. This protocol stability is a feature, not a bug : Bitcoin evolves slowly because any protocol change requires distributed consensus, and the risk of a bad change far exceeds the cost of waiting. The consequence is that in 2026, innovation moves : fewer Layer 1 modifications, more constructions on existing primitives (Taproot, MAST×MAST (Merkleized Alternative Script Trees)Structure introduced with Taproot: several spending conditions for the same UTXO, organised as a tree. Only the branch actually used is revealed on-chain, the rest stays private.See in the lexicon →, MuSig2×MuSig2Schnorr signature aggregation protocol (BIP 327). Lets multiple signers produce a single signature indistinguishable from a single-signer one.See in the lexicon →).

Several structuring proposals are nonetheless under active discussion. Covenants (OP_CTV BIP×BIP (Bitcoin Improvement Proposal)Standard document that describes a proposed improvement to the Bitcoin protocol. Numbered (BIP 32, BIP 39, BIP 174, and so on). Open, public process on GitHub.See in the lexicon → 119, OP_VAULT×VaultCustody setup for long-term storage, often multisig, kept offline and touched rarely.See in the lexicon → BIP 345, ANYPREVOUT BIP 118) would open a new class of contracts with restrictions on future spending. The Ark protocol (Burak Keceli, 2023) offers a Lightning alternative for payments without inbound liquidity×Inbound liquidityCapacity of a Lightning channel to receive payments. To get paid 100,000 sats, you need at least 100,000 sats of inbound liquidity available.See in the lexicon →. BitVM (Robin Linus, 2023) enables off-chain compute verifiable on-chain, opening ZK-rollups on Bitcoin. Layer 1 ZK-proofs remain a research direction.

This article maps the 2026 state of these evolutions, lays out their use cases and risks, and proposes a hypothetical 2027-2030 calendar. It is informed prospective, not prediction : no soft-fork is guaranteed, and the debate is open. CLOSING of Sprint 8 "Advanced Bitcoin", and end of the topic.

Covenants in discussion : OP_CTV, OP_VAULT, ANYPREVOUT

The covenants debate is the most structuring open one in 2026. Three distinct proposals coexist. OP_CTV (BIP×BIP (Bitcoin Improvement Proposal)Standard document that describes a proposed improvement to the Bitcoin protocol. Numbered (BIP 32, BIP 39, BIP 174, and so on). Open, public process on GitHub.See in the lexicon → 119, Jeremy Rubin 2020) is the minimal covenant×Covenant (CTV, OP_CHECKTEMPLATEVERIFY)Programmable restriction on how bitcoins may be spent in the future. Proposals like CTV (BIP 119) would open the way to vaults and improved channels; the community debate is ongoing.See in the lexicon → : restricts the exact shape of the future spending transaction. OP_VAULT×VaultCustody setup for long-term storage, often multisig, kept offline and touched rarely.See in the lexicon → (BIP 345, James O'Beirne and Greg Sanders 2023) is more structured and dedicated to time-locked vaults. ANYPREVOUT (BIP 118, Christian Decker and Anthony Towns) opens a different path, mostly for Lightning Eltoo.

These proposals are not mutually exclusive but compete for community attention. The pro-covenant argument : they unlock a whole class of use cases (vaults with withdrawal delay, institutional vaults, trustless recurring payments, efficient Lightning channel×Lightning channel2-of-2 multisig between two participants that lets them exchange sats off-chain as many times as they like, until they close the channel and publish the final balance on Bitcoin.See in the lexicon → factories). The against argument : they add significant protocol complexity, and some fear they create fungibility or censorship risks (a covenant prohibiting certain destination addresses, for example).

State in 2026 : the three proposals are in Draft or Proposed. CTV is the most technically mature but saw its champion (Rubin) leave the project in 2023, which slowed its momentum. OP_VAULT has a clear use case (institutional vaults) motivating several custodians. ANYPREVOUT has strong Lightning community support. A 2027-2028 activation remains plausible but requires social consensus on which of the three goes first. The Delving Bitcoin debate is lively.

Ark : a Lightning alternative without inbound liquidity

Lightning's number one operational issue remains inbound liquidity×Inbound liquidityCapacity of a Lightning channel to receive payments. To get paid 100,000 sats, you need at least 100,000 sats of inbound liquidity available.See in the lexicon → : to receive, a channel must be pre-funded on the remote side. Ark (Burak Keceli, 2023) offers an alternative structurally solving this problem. Instead of peer-to-peer channels, Ark organises users into rounds coordinated by a service provider (Ark Service Provider, ASP).

The mechanism : at each round (every few minutes to a few hours depending on deployment), all participating users send their virtual UTXOs (vTXOs) to the ASP. The ASP builds a single Ark transaction on Bitcoin Layer 1 consolidating everything. Between rounds, vTXOs transfer off-chain among users without touching the blockchain×BlockchainA public, shared ledger that records every Bitcoin transaction in blocks linked together cryptographically. Each participant in the network keeps a copy.See in the lexicon →. To receive a payment, you just give an Ark address to the sender ; no pre-funded inbound liquidity is required.

Ark technically needs covenants (CTV or similar) to work fully. A temporary variant (clArk, covenantLess Ark) offers a covenant×Covenant (CTV, OP_CHECKTEMPLATEVERIFY)Programmable restriction on how bitcoins may be spent in the future. Proposals like CTV (BIP 119) would open the way to vaults and improved channels; the community debate is ongoing.See in the lexicon →-free version, costlier but deployable today. Several experimental implementations are running in 2025-2026 (Second.dev, Bark, Boltz Ark). If covenants get activated, Ark could become a complementary or alternative path to Lightning for some uses (mainstream micro-payments, integration into retail wallets).

BitVM : off-chain compute verifiable on-chain

BitVM (Robin Linus, October 2023) is probably the most surprising proposal in the Bitcoin ecosystem since Lightning. The idea : let two parties run an arbitrarily complex computation off-chain, with cryptographic guarantee that if one cheats, the other can prove the cheating on-chain and trigger a sanction. And all this without modifying the Bitcoin protocol : BitVM uses existing Taproot×TaprootMajor Bitcoin upgrade activated in November 2021 (BIP 341). Brings more privacy, scripting flexibility and the efficiency of Schnorr signatures.See in the lexicon → and Tapscript×TapscriptScript language introduced by Taproot (BIP 342), an extended version of Bitcoin script with new opcodes. Technical basis of recent uses, from native multisigs to inscriptions.See in the lexicon → primitives.

The mechanism relies on interactive challenge-response on the Bitcoin blockchain×BlockchainA public, shared ledger that records every Bitcoin transaction in blocks linked together cryptographically. Each participant in the network keeps a copy.See in the lexicon → and massive cryptographic commitments. The compute itself happens off-chain ; on-chain transactions only serve dispute resolution. Practical application : you can build Bitcoin bridges to other chains, complex smart contracts, and even ZK-rollups where Bitcoin serves as settlement layer.

BitVM2 (Linus and colleagues, 2024) refined the design to reduce cost and the number of transactions needed in case of dispute. In 2025, several teams (Citrea, Bitlayer, Build on Bitcoin) announced sidechains or bridges using BitVM. Operational maturity remains limited in 2026 (still in research-to-production phase), but the conceptual importance is major : BitVM shows that Bitcoin can serve as settlement layer for a vast class of applications without soft-fork×Fork (soft fork, hard fork)Change to the protocol rules. A soft fork stays compatible with old nodes (SegWit, Taproot); a hard fork creates a separate chain (Bitcoin Cash in 2017).See in the lexicon →. It is probably the most dynamic new frontier of the ecosystem.

Zero-knowledge proofs Bitcoin-side

Zero-knowledge proofs (ZKP) gained maturity on the Ethereum and Layer 2 side between 2022 and 2026. On the Bitcoin side, ZK integration is slower but accelerating. Three distinct angles exist. First, wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon →-side ZKPs : light wallets using ZK to prove membership in a UTXO×UTXO (Unspent Transaction Output)« Chunk » of bitcoin received and not yet spent. A wallet does not have a single balance, it has a collection of UTXOs whose sum makes up the balance.See in the lexicon → set without revealing which (Sapio-style concept, still very experimental). Second, ZK-rollups on Bitcoin via BitVM : Citrea (Chainway) and several other projects build an EVM-compatible rollup whose proofs are verified via BitVM. Third, native ZK opcodes (OP_ZKVERIFY or equivalent), proposed but without formal BIP×BIP (Bitcoin Improvement Proposal)Standard document that describes a proposed improvement to the Bitcoin protocol. Numbered (BIP 32, BIP 39, BIP 174, and so on). Open, public process on GitHub.See in the lexicon → in 2026.

The argument for integrating ZK-proofs on the Bitcoin side : opening up a new class of privacy-preserving applications (hidden accounts, membership-proof transactions, etc.) and competitiveness versus Ethereum/Solana on use cases requiring expressivity and confidentiality. The argument against : massive protocol complexity, cryptographic risk (ZK schemes rely on security assumptions more recent than ECDSA×ECDSALegacy signature algorithm used by Bitcoin before Taproot. Signs a transaction with a private key to prove ownership.See in the lexicon →/Schnorr×SchnorrMore modern signature algorithm, activated by Taproot in 2021 (BIP 340). More efficient, enables signature aggregation (MuSig2).See in the lexicon →), and dev attention fragmentation risk.

State in 2026 : no serious native ZK BIP, but a lot of R&D off-chain and via BitVM. Bitcoin and ZK communities are slowly converging, several Bitcoin++ and ZK Summit conferences see cross-pollination. No activation envisaged before 2028 at earliest, but the direction is plausible on a 10-year horizon.

Hypothetical 2027-2030 calendar

None of what follows is certain. Bitcoin evolves through distributed consensus, not roadmap. But 2026 indicators allow a hypothetical calendar for the next years.

2027. Likely activation of a first covenant×Covenant (CTV, OP_CHECKTEMPLATEVERIFY)Programmable restriction on how bitcoins may be spent in the future. Proposals like CTV (BIP 119) would open the way to vaults and improved channels; the community debate is ongoing.See in the lexicon → (CTV or OP_VAULT×VaultCustody setup for long-term storage, often multisig, kept offline and touched rarely.See in the lexicon →, more likely CTV given its technical maturity). Activation mechanism still to choose (Speedy Trial 2 or BIP×BIP (Bitcoin Improvement Proposal)Standard document that describes a proposed improvement to the Bitcoin protocol. Numbered (BIP 32, BIP 39, BIP 174, and so on). Open, public process on GitHub.See in the lexicon → 8). First mainstream Ark applications on covenant if CTV passes. BitVM2 reaches production maturity with several operational sidechains. Sparrow Wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon → and Specter integrate native JoinMarket. BIP 352 silent payments become majority on retail wallet side.

2028-2029. Bitcoin halving×HalvingScheduled event every 210,000 blocks (roughly every 4 years) that cuts the miner reward in half. This mechanism makes Bitcoin issuance decline towards the total cap of 21 million.See in the lexicon → (April 2028) with block reward dropping to 1.5625 BTC. Historically expected 2028-2029 bull cycle. Potential ANYPREVOUT activation for Lightning Eltoo if CTV is well integrated. First scale deployment of Ark if covenants mature. Bitcoin ZK-rollups via BitVM reach a few million users.

2030 and beyond. Potential OP_VAULT activation for institutional vaults. Discussion on native ZK opcodes takes form. Bitcoin Layer 1 stays stable and conservative, innovation concentrates on Layer 2 (Lightning, Ark, BitVM-rollups) and sidechains (Liquid). The diversity of layers above Bitcoin strengthens, without concession on the simplicity of the monetary base.

What will not change and topic closing

Amid possible evolutions, some Bitcoin invariants remain guaranteed by construction. The 21 million×21 millionMaximum number of bitcoins that will ever exist, hard-coded in the protocol. This programmed scarcity is a founding feature. The last sat will be mined around the year 2140.See in the lexicon → BTC cap stays fixed by consensus rules since 2009 ; no credible change is in discussion (the debate itself is social taboo in the community). The reward halved every 210 000 blocks continues its deterministic rhythm until 2140. Mining×MiningProcess of validating blocks through proof of work. Consumes electricity by design : that is what secures the network.See in the lexicon → difficulty adjusts every 2 016 blocks as it has since block 1.

The commitment to monetary neutrality also remains an invariant : Bitcoin has no central roadmap, no leading foundation, no pre-mine for insiders, no token-voting governance. This absence of structure is its resilience. BIPs, soft-forks, Layer 2 and sidechains build around it, but the monetary core remains touchable only by near-unanimous distributed consensus, which in practice only happens for conservative changes.