It’s about 1.1TB for full sync geth nodes, and growing. Ethereum researchers are looking into statelessness and state expiry which aim to make it even easier to run nodes with little need for space.
People will continue to run nodes regardless of the price of ETH, just like Bitcoin.
ENS is a smart contract protocol, so I don’t see how it’s related.
Most L2s will require users to pay transaction fees in ETH. Some will have fee abstraction where people can pay with tokens, but the rollup themselves will still end up paying ETH on L1.
Ethereum will essentially be a settlement layer for rollups, and everyone will be doing their DeFi, NFTs, etc on the rollups which are almost treated like their own chains.