Give your views will Bitcoin currency replace all the digital currencies and become the most used currency in future
Why you have to think about future to come to that conclusion ? Its already there.Maybe something like bitcoin would be used officially to buy stuff on airports and government organisations.Maybe buy train tickets with bitcoins.Pay for your bus fares with bitcoins.Hope you do get the point.Bitcoin will be widely used and accepted like dollar in future for sure, the only thing is we need to wait for sometime for it to happen, bitcoin will be the best currency in future.
Due to it's growing higher potential market, it has very bright future 
All online shops are going to accept bitcoin similar to paypal in future
The transaction confirmation is too slow at the moment. We need the speed to be much faster than now.