Bitcoin ofcouse is the main cryptocurrency but what do you guys think of long term value of Ethereum? seems that developers do not like it much but its applications seems limitless. could it surpass bitcoin in future?
The main thing to believe! If you are interested in this coin, you mean you earn it. Just believe and everything will come true. 
I do not feel so that any coin can takeover btc in coming next 5 years. May be their demand may increase as the btc price becomes more expensive people might switch to altocins so that its affordable to them as well. This may result in a better chance of some of the good coins to march towards the highness of btc but beating them will be a tough ask.
we cant say it yet because we cant foreseen what will happen on the future and besides there are many new good coins these days that are popping out like a mushroom and some of them has actually a potential with good purpose that is somehow usefull in anyways , so i guess maybe these coins can surpass and beat bitcoin someday. although i believe that bitcoin can still go a long run and will continue to maintain its high value.