i think bitcoin is already an international currency because i see that nowadays bitcoin is acceptable in everywhere and bitcoin transaction is very faster than other currency and we can say that bitcoin is already international currency.
I agree with you could see bitcoin users already spread all over the world, almost every country may have bitcoin users, it means bitcoin can be used in all countries, and it proves that bitcoin is an international currency
Indeed, considering such aspects Bitcoin can be seen as a currency of international use, but the concentration of people who uses the currency in every country is still low, so I think there is still a lot to be achieved. The upside is that the ecosystem is growing rapidly, and we will be able to see several merchants adopting the currency for years to come.