Brandability, network effects, first to market… these will keep BTC on top. To all those who cite MySpace -> Facebook as support for extrapolating recent BTC/ETH price movement, I offer a different example: all the tech and features that Facebook adopted long after small startups pioneered them. When you're on top, you can afford to move slower, because all the strivers beneath you will invent them for you and you can absorb whatever rises to the top. Ethereum has made some great contributions to crypto tech, and it will be exciting to see their best ideas incorporated into the Bitcoin platform.
No, it's not all about the tech – not for normies, anyway. It's about brand. Remember when you could only get an iPhone with AT&T, and the service in NYC was so spotty? It didn't stop people from carrying iPhones.
Now Apple is a trillion dollar company, almost, when many would argue that the Android phones have offered better tech for some time now. Yet there is still a huge market for Android, and in this analogy that is the role I see for Ethereum. So I would recommend diversifying, but wait for the dip.