I think NEO that closest to Etherium can even replace Etherium
NEO is closest to Ethereum but it is not predictable that Ethereum can be replaced with other coins. Ethereum is playing major role in Crypto world because of it is popularity and consistency. Ethereum value is also growing 1ETH=$285. None other coin except bitcoin has this much value. Ethereum will rock for sure.
Ethereum is a good coin due to the way it change cryptocurrency market but the future of ethereum can be predict mate because NEO and Ethereum offer the same concept and as at now NEO can process more transaction than Ethereum. Although, Ethereum team promise to create sharding which will be the answer and they are yet to create. So, they don't create it there crypto sphere will switch to NEO.