Ethereum’s Glamsterdam Upgrade Set for Sepolia on Oct. 6

The Sepolia date matters less as a testnet milestone than as the first real read on whether enshrined proposer-builder separation behaves under live conditions, since that change touches the core of how blocks get built and who captures the value in them. Block-level access lists and new gas pricing cut a different way, affecting execution efficiency and fee outcomes for anyone transacting or building on the chain. With no mainnet date set, the open question is whether Sepolia surfaces friction that pushes that timeline, and how the builder and relay landscape repositions in the interim.