Crucially, rollups are secured by the mainnet, thus not materially sacrificing decentralization. We already have multiple rollup solutions on Ethereum mainnet today -zkSync, Looping, dYdX, zkSwap, DeverseFi, Synthetix staking, ImmutableX etc. All of these require zero gas (not exactly zero, but so low they are subsidized by protocols currently) and can process thousands of transactions per second on Ethereum, with transactions completing in under 1 second, offering us a glimpse of the future.