Please stop this kind of topic. There's no point discussing who will be the next Ethereum. Since a few years ago, there have been discussions like this and a lot of tokens and coins have been said to be the next Ethereum.
But not any of them did follow the path of Ethereum.
I agree with your statement because your point is completely valid. This is not kind the topic for the discussion. There is only one ETH and there are no other coins that would replace ETH or take its place. As per the above post, many people have claimed this thing already and some of the people have had suggested many coins names to replace ETH but none of it had capable to take place of ETH.
If we talk about replacing it on the current rankings maybe the xrp is the biggest contingent and we already see it for so many times where it the number 2 spot base on the cmc rankings. But for other new coins claiming to be the next ETH well I doubt there's no one can do that since first this coin is been here and got a good adoption that's why it's so hard to get overpowered by the other who claims that they are great.