This is a very hard question, and I am sure nobody can answer this. Everything is just guessing.
Everybody is tryin to predict, but to be honest, nobody can.
It is kind of gambling, but the more knowledge you have, the better your odds get.
Since the demand is increasing and will increase, I think there is no limit.
The only thing which threatens this Bullish rising is a new coin or some goverment issues.

50k end of 2018 is my predicition.