it will happen for sure but not in a way we are thinking. It will not be an overnight process but you will slowly see ETH climbing up the stairs to become the best cryptocurrency. Of course there is pretty valid reason as to why Ether will replace btc its much faster in transaction speed and same with cost. But what's the best thing about ETH is that it is substantially more stable as of now atleast. It has a lot of tokens listed over it so any slightest of change in it affects the whole market.