Very hard to predict because it depends on so many factors - new user interest, speculation, actual use of it as a currency, etc.

If I had to take a guess - it'll go to $100.  Sounds crazy, but I believe that demand will exceed supply for quite a while to come.. and that's why the price should continue going up in the long term.  I remember when people sold at 5 cents because they had made 10 times their money, and nobody thought it would ever go to 10 cents.. that kind of thinking was 'delusional'. Yet look at where we are now. 
If nothing else, Bitcoin is a fascinating experiment at a true free market driven by supply & demand