I'm sure ETH price will going strong this year.
But not that strong.
If ETH price USD 15k, ETH rank on coinmarketcap will beat bitcoin place by 10 times or more, which is impossible since bitcoin is mother of all coins and its position is almost never unbeatable.
But, if bitcoin price is also 10 times by now, it's possible ETH price will be that high
Bitcoin will not be 10 times higher by the end of 2018 and Ethereum will not hit $15000. If Bitcoin could end the year above $8000 I would be happy.
all depends on price movement of bitcoin. whether the future will have a high or low price. as indeed this would be an increase factor of ethereum and altcoin