the more it is popular around the world and the more people accept it the better as it is causing price rises and so on
I do think that Bitcoin already is a global currency to be honest because you can make use of it if you have access to the internet.
Technically yes it's a global currency since it can be used worldwide without any restriction in most of the country.
Also the capability to earn this currency thru various way in the internet making it more accesible by most of the people in the global, hence making it as a strong global currency.