Ethereum is the king of altcoins and will remain so for a very long time to come, I'm still not confused that Polkadot is capable than Ethereum, I've seen few altcoins that entered top 10 in the past and later goes down under top 10 rank, it's too early to start praising Polkadot, I hope it lives up to people's expectations but don't dare dream of Polkadot beating Ethereum, it's not going to be easy for a new altcoin to achieve what Ethereum have achieved since years back