On before this time there have been many forms of means of money so if bitcoin happens to become global currency today there is nothing wrong with it. but for the time now i really don"t see it coming because just some few many know about bitcoin for the now with time it will be well know to everyone.
For now we are just few users of bitcoin and i think more adoption are needed in order bitcoin to become a global currency..
We are lucky that we are early to know about bitcoin and hoping that more company are accepting bitcoin as payment..
We are far that bitcoin to become global currency because bitcoin still not acecptable by many companies online but maybe in the future if more adoption and develop business will release in the future i am sure we will see that bitcoin will be global currency..