Vitalik Buterin has revealed Ethereum's long-term roadmap, dubbed "Lean Ethereum," which aims to transform the protocol over the next three to four years. This initiative, discussed at a recent meeting in Berlin, is set to be as significant as "The Merge," involving comprehensive refactoring of core modules. Key developments include the introduction of recursive STARKs for verification, enhancing quantum safety by replacing vulnerable components, and improving the consensus layer with decoupled availability chains and faster finality. The state layer will see the addition of scalable state types, potentially reducing gas fees by over tenfold post-migration of applications like ERC20 and NFTs. Privacy enhancements and the introduction of leanISA or RISC-V to the VM are also planned.