Ethereum was not made to over took bitcoin from the beginning and we have to look at ether as a different technology outside bitcoin. Bitcoin is like a central bank to others coins and of a truth it has been serving that purpose. Ethereum's scalling is not going to be an issue as a lot of advisement is been add every days. Bitcoin market capitalization in 5 years to come may be above 500,000,000,000 billions and I don't think ethereum will have investors trust to get to that level.