I don't think there is any coin that will become the next Etehreum. It's very hard to overcome the ethereum. Ethereum is just not only a coin, it is a supercomputer. Most of the altcoins are using Ethereum smart contracts to create their coin. It has great community support, huge liquidity, all of the exchange-listed ethereum at their exchange, Its has a great real-life use case.

However, If there is any alternative to ethereum, that will be TRON in my point of view. It has great community support, a very active team, a good market cap, huge liquidity at an exchange, a very low cost to make a transaction, and it's very fast. It has own blockchain and peoples also using this blockchain a lot.