Vitalik Just Dropped Ethereum's Block Building Future Plan

Vitalik Buterin laid out Ethereum's entire block building overhaul in a single X post. The plan touches censorship resistance, MEV, transaction privacy, and long-term distributed infrastructure. All at once.

Buterin posted on X that the Glamsterdam upgrade brings ePBS to Ethereum. That change lets proposers hand off block building to an open, permissionless builder market. The separation stops block builder concentration from bleeding into staking power.

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FOCIL Is Ethereum's Censorship Kill Switch

FOCIL is the first live piece of this. Sixteen randomly picked attesters each select a small set of transactions. Those transactions must appear in the block. No exceptions. A hostile builder controlling 100% of block production still cannot exclude them.

As Vitalik Buterin said on X, if those transactions are missing the block gets rejected outright. That is the enforcement mechanism. Hard coded. No workarounds.

A bigger version is being discussed too. "Big FOCIL" would let the selected group cover the full transaction set. The i'th attester handles senders whose address starts with the i'th hex character by default. Censored transactions from previous slots get picked up automatically, at the cost of one slot delay.

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The long-term version of this pushes builders into a narrow role. They would only handle MEV-relevant transactions like DEX arbitrage. Everything else gets handled at the attester layer.

The Hidden Attack Nobody Talks About

Encrypted mempools come up next. Vitalik Buterin, in the same X thread, pointed to sandwiching and frontrunning as the core problem. These are not edge cases. They are systematic attacks on ordinary users.

The fix is encrypting transactions until after inclusion. No one wraps a hostile trade around something they cannot read. The technical challenge is guaranteeing validity and decryption at the right moment without breaking mempool efficiency.

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What gets less attention is the network layer. Vitalik flagged this directly on X. Between a user sending a transaction and it landing in a block, a hostile observer watching cleartext traffic can sandwich it, grief it, or unmask a privacy protocol user entirely. RPC providers see everything. Analytics firms running many nodes see everything else.

Work is underway on network-layer anonymization. Tor routing for transactions, custom Ethereum mixnets, and latency-minimized non-mixnet designs like Flashnet are all being explored. Buterin said the kohaku initiative is expected to integrate pluggable support for these protocols.

Ethereum as BitTorrent

The most speculative part is the longest game. According to Vitalik Buterin on X, the goal is making Ethereum process transactions the way BitTorrent handles files. No single server ever needs to see the whole picture.

The problem is Ethereum's synchronous shared state. Any transaction can in principle depend on any other. That dependency centralizes building. Even Big FOCIL only handles it partially.

One proposed path creates new lower-cost transaction types with reduced global scope. Most activity does not need full global state access. The 5% that does tends to be high value. Keeping those expensive while making lighter transactions much cheaper could open the door to genuinely distributed block production.

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None of this is finalized. Buterin described the distributed building direction as an open and exciting long-term design space. But the framing is deliberate. Ethereum is not treating these as separate problems.