Ethereum co-founder Vitalik Buterin has declared the blockchain trilemma solved following the December 2025 Fusaka upgrade. The protocol is shifting toward distributed block building to prevent builder oligopolies from controlling transaction inclusion. Experts like Mo Dong note that while technically complex, the real challenge is incentive alignment, as distributed building complicates MEV extraction.
In what has been described as a victory lap for the ecosystem, Ethereum co-founder Vitalik Buterin recently declared that the network has officially solved the blockchain trilemma. This milestone was achieved through “live running code” that transitions Ethereum from a traditional replication model to a more efficient distribution model.
The turning point arrived with the Fusaka upgrade in December 2025. This upgrade integrated PeerDAS, or data availability sampling, into the mainnet, marking the final protocol improvement needed to resolve the trilemma challenge. The upgrade delivered massive performance gains, with proving times dropping from several minutes to approximately 16 seconds. Furthermore, the network achieved a state where 99% of blocks are now provable in under 10 seconds.
Read more: Fusaka Upgrade Lands Tomorrow — Ethereum Set to Gain Strong L2 Data Flow and Sharper Gas Controls
Beyond raw speed, the protocol is now focusing on total censorship resistance. In a recent post on X, Buterin introduced a vision where a full block is never assembled in a single location, aiming to prevent a small oligopoly of block builders from controlling transaction inclusion.
While distributed block building is vital for neutrality, critics highlight significant hurdles. Mo Dong, co-founder of Brevis, noted that the primary obstacle is not code, but incentive alignment. Because distributed building means no single party sees the full transaction set before finalization, it complicates maximal extractable value, or MEV, extraction.
“The path forward likely combines in-protocol mechanisms like FOCIL, which forces proposers to include transactions meeting certain criteria, with out-of-protocol solutions like distributed builder marketplaces,” Dong said. “Neither alone is sufficient, but Ethereum can incrementally reduce centralization in block building while the research matures.”
Despite these technical wins, there is still a sense that the user experience remains fractured and liquidity remains fragmented. This suggests that more work is needed to fix the challenging interoperability between layer 2s and the Ethereum layer 1.
According to Dong, the gap is closing, and the core problem is coordination rather than technology. “We know how to build bridges and verify proofs across chains,” he said. “What we lack is standardization: every L2 has its own bridge contracts, message formats, and finality assumptions. Users experience this as fragmented liquidity and confusing UX.”
Dong also believes zero-knowledge proofs are changing this equation. Verifying a layer 2’s state transition cryptographically eliminates the need for challenge periods or trusted validators, which dramatically simplifies cross-chain communication. Dong estimates that within a few years, average users will move assets between major layer 2s without having to think about bridges at all.
Meanwhile, the 2025 end-of-year report highlighted a new frontier: the finalization of ERC-8004 and the adoption of the x402 payment standard. These developments have turned AI agents into autonomous economic actors. As these agents transition from testnets to processing significant capital on the mainnet, critics warn of legal and systemic risks within a machine-to-machine economy.
Currently, Ethereum’s account abstraction provides the necessary guardrails for this transition. Regarding the legal risks, Dong noted that the landscape is genuinely uncharted because current legal frameworks assume human intent, which breaks down with autonomous agents.
“Systemic risks are more tractable. Account abstraction enables programmable guardrails: spending limits, rate limiting, and automatic circuit breakers,” Dong said. “But guardrails only work if they’re enforced, and enforcement requires verification.”
Dong argued that the agents handling significant capital will be those that can cryptographically prove their behavior stays within defined constraints, rather than simply promising to do so.
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