For me ETH will not pass BTC in 2019 or the year onwards. It will stay beyond the BTC and there is no chance it will increase.
It will/may increase more than btc on according to their current ratio but not base on their full price. For example, btc may increase 50$ and ethereum may increase 15$ so it is more than btc base on their current price ration. But it would not be ever possible to pass btc.