It may be possible, but is it desirable? Different areas have different economies at different times and that may be best served with local currencies.
I think it’s possible because in near future every country is to bound to legalized the bit coin and when it’s become a legal currency in the countries of the world so then there will be no need of local currency when someone is going abroad from his her home country , simply he she will have bit coin in his her wallet and whenever he she wants to make transaction like doing shopping, eating in restaurants etc. so he she will just use his her bit coin easily and will have no worry of ending the balance because by ending the balance he she can easily take loan from his her friend from any core of the world.