Etherum overcome bitcoin, i don't think that can happen even in the future. Bitcoin has been taking the lead for so long, all other cryptocurrency follows BTC. Even if things change. I still don't get how ether will overcome bitcoin.
I also think that way, at this time ethereum price still follow bitcoin price. So how eth can overtake bitcoin. If it happens it will take a very long time, because bitcoin is the oldest coin of all coins today.