No. There is no such thing as next Ethereum. There will be one and only Ethereum and the rest of the altcoins that wanted to be on Ethereum's track will be different and will just be following Ethereum. How many times have we heard of altcoins claiming to be the next Ethereum? I heard that from Binance (BNB), Cardano (ADA), etc. So far, Ethereum is still the one and only.  

Tezos has always been an incredible project. It should push forward not under the shadows of Ethereum but on its own light. It could very compete as Tezos and not as the next Ethereum.