I think it will take some time.  Ethereum is still lagging in many aspects.  One of which is the government acceptance.  Bitcoin had established its acceptance in several countries already, while ETH hasn't shown us that side yet.  Bitcoin had been the main talk of the different countries whether to accept it or not, ETH. I don't read any (please send a link if you have read one).  It is always been Bitcoin that lead the cryptocurrency on its way to global adoption.  So I think, that even if ETH surpasses BTC in terms of CMC, Bitcoin will always have dominance.