Why not? We can see rapid use of bitcoin everywhere. Then if it used largely it will be an international currency
But, i think it's verry impossible, couse bitcoin have many weakness like anyone can get it with verry easy. And if wold be, that can make bitcoin unlimited, so if all people have so many bitcoin, it will make bitcoin verry cheaper after.
Bitcoin could end up being a side nation's country money but the fact of the matter is... You cannot expect btc to rise to the challenge to be that currency because there are a limited amount of btc allowed.