What exactly is Ethereum taking over? It's already at the top. If you're referring to ETH taking over Bitcoin, then you're very wrong because that's not going to happen. Ethereum is already at its right position and that's where it's going to stay or even fall back. None of these altcoins will be taking that number one position on Coinmarket.com, that's a position that's meant for Bitcoin. Even if that's going to happen it's going to take a very long time.

Ethereum is good, and other altcoins are good, but none of them are really going that far, because being the first cryptocurrency has already given Bitcoin the advantage. And moreover, most of them are even pegged to Bitcoin.