Ethereum is good altcoins, but I don't think 2018 ethereum next year, too hard to predict it. Bitcoin will stay it top cryptocurrency and might Ethereum will remain in the second place of cryptocurrency. For me, a lot of the altcoin want to be the second place like a ripple. I sure that bitcoin will take the lead and maybe Ethereum or Ripple take the second spot.
Bitcoin is always the king of Crypto currency,Ethereum will be the next.Litecoin will be in the third place.May be any changes may occur,any will replace the third place .The Waves,Monero and Ripple have some chances for the third place.Because it have more potential as like Ethereum.