No doubt about it bitcoin now is being used as global currency by those people who only know bitcoin but still we may say that it is still not applicable or quite sort of. But in conclusion, there are people from different countries that has been using bitcoin in the long run as investment, currency and trading platform globally.
Though bitcoin is used all over the world by people living in different countries, but it is still not that much a global currency as it is not yet legalized or used in many countries, i heard only about a few countries where bitcoin is used or accepted in physical world otherwise it is just a internet currency.
But it can be also legalize when majority of the people are using it even it is still not being considered by the government. So if the people are shouting to legalize bitcoin and adopt it as global currency then the government will don't have choice but to legalize it. As they do believe in Vox Populi.
And how will we be in their control after they'll legalize Bitcoin and make it an official payment method? The politicians are looking to control as much as they can so they can steal as much as possible from us. Most of our money (and I'd say it's over 75% of it) goes to their pockets, unlike the promises they're making everytime before they're elected. It's all about beautiful words, you know.