Yes, to become an international currency, bitcoin must be known by all people around the world. For now, bitcoin is not become a global currency, because there are many people that still don't know about bitcoin and how it works.
I beg to disagree, as far as I know there are people in different country though they are in a small percentage, known bitcoin and using it in their daily to monthly lives. I think that is enough for me to consider bitcoin as global currency. The mere fact that exchanges accept bitcoin and exchange it to their respective local fiat shows that it is really a global currency.