Bitcoin is already universal virtual currency, widely used in all over the world.
Of course, we are not mainstream yet but coming closer to this goal.
In the long term I'm sure that everybody will accept Bitcoin as standard payment option because other payment services can't offer to users what we can (fast transaction, security, anonymity, no banks involved etc.).
Yes, there are people using bitcoin all over the world but "universal" kind of implies that everyone uses it, and that's nowhere near true. I would also argue that bitcoin isn't getting much use as a currency. No one buys stuff at the grocery store in bitcoin, gas, utilities, rent, sex toys, all of these things are paid for 99.999% of the time with fiat. Bitcoin has a loyal following, yes, but people just don't want to spend it.