Ethereum is set to become the only major blockchain offering both theoretically optimal security under synchrony and strong economic finality under asynchrony with the full deployment of @leanethereum. This advancement will require 51% of online validators to be honest, ensuring robust security. While most semi-centralized fast chains focus solely on economic finality and Proof-of-Work (PoW) chains prioritize security, Ethereum will uniquely provide both features, enhancing its position in the blockchain ecosystem.