I think it depends on bitcoin destiny. If bitcoin hard fork will success then ethereum will lost his price a lot. Because now ethereum price grows up so fast because of fear before bitcoin hard fork of some investors. My price is between 1,500-3,000$. When bitcoin price should be not less then 10,000$. I am very optimistic 
Some says bitcoin prices might goes up to 100.000 dollars. So are you sure that you're optimistic?
In 5 years, we'll be talking about the year, 2022, where bitcoin block halving will have taken place 2 years ago. We'll observe huge price movements.
Haha. Well, yes that's true. Haha. After a little thought, I would have to agree. I have noticed that BTC always double each year (on average) from each yearly low. And every time the reward halves, the angle of the growth increases equal to the half value.
But honestly, ETH is not a block chain, its smart contracts. Smart contracts are the next generation. BTC is the first generation. BTC is meant for larger money assets, not little dinky dinky chump change. I think ETH could very well be worth more than BTC. ETH is going to be used for thousands of things, like trading electricity between counties or state to state. This is contract trading.
My guess is more than BTC at some point, but I don't know if it will stay higher in price.