The fact is that Bitcoin has reached a price that seems really incredible, as in the beginning it costed nearly zero. For that, and even 50k sounds absolutely impossible to me, the thing is that ... who knows.
But Ether is a different thing. Ether is being insistently used for ICO and that means that it goes in and then it goes out, so the value is not dependen on scarcity and I think that can´t reach the same height.