Ethereum's Vitalik Buterin Unveils Plan to Tackle Block Builder Centralization

Ethereum co-founder Vitalik Buterin has outlined a multi-stage plan to combat block builder centralization and MEV (Maximum Extractable Value) on the Ethereum network. The plan is part of the upcoming Glamsterdam upgrade, which is expected in the first half of 2026.

Glamsterdam will introduce enshrined Proposer-Builder Separation (ePBS) directly into Ethereum's consensus layer, separating the roles of block proposers and builders. However, Buterin argues that this does not resolve the risk of a small number of builders dominating and censoring transactions.

To address this issue, Buterin proposes FOCIL (Fork-Choice Enforced Inclusion Lists), which allows 16 randomly selected attesters to nominate transactions for inclusion in the next block. Any block that ignores these nominations will be rejected by the network.

Buterin also outlined a more speculative extension of FOCIL, called 'Big FOCIL', where the inclusion lists grow large enough to cover all transactions, potentially reducing a builder's role to ordering only MEV-relevant transactions.