No the bitcoin will not replace the dollar because the bitcoin is too small what already has been mentioned.
I think soon or later it could be possible but anytime soon it will not happen because too many people are depending on the dollar and the bitcoin is even depending on the dollar these days..
Bitcoiin and dollar are two different concepts and I think bitcoin will never replace dollar, bitcoin is like gold and not a currency in my opinion.
It will not replace soon as you can see now you see of course that Bitcoin is getting more popular but there are also a lot of people that is still using Dollar.
And many people doesnt even know how Bitcoin works and that is the problem so first you have to fix that problem and than you can talk about replacing.