I think it might be possible because bitcoin comes with so many benefits and advantages that might be any country's whee it's people will use more bitcoin than regular Fiat will make it their national currency.  I believe that you can not predict anything in case of bitcoins.  But with due time there are very chances that people will invest more and more in bitcoin.  So there are possibilities that it may become the worldwide currency.  The system of currency is running from so long.  And this digital advancement is the knock of future on our door steps.