Isn't it alreday an international currency? I think it is. Since people around the world begun to use it it has begun global, international currency. Today I think it is used on all continents. Will it be officialy recognized as such, that is another question.
Being international on internet is something else but OP is talking about being international in physical world which means it would be accepted everywhere in the world, and that does not seem to be happening so soon but hopefully it will be done one day.