This is impossible because etherium is still unable to deal with a surge in transactions so that a lot of transactions are not resolved and failed and this is a logical problem that makes prices weaker and bitcoin seems to remain the leader of all coins for the time being until 2020 still
First of all there is no impossibility in the world. Everything is possible. About ETH vs Bitcoin, see that the pace at which ETH started growing back then was far more accelerated than that of Bitcoins. I agree that ETH is down now and it cannot be thought of as a potential competitor but if we extent out thoughts in the long run, it is not impossible at all. There is possibility ETH give a hard time to Bitcoin again because the product with the latest and advanced features is preferred over the traditional one.