Of course, Bitcoin can be a world currency. However, Bitcoin is not valid in all countries. But seeing the popularity of Bitcoin,it will be the world currency for a time.Only the bitcoin has been known in all the countries, which could not make any other coins.Everywhere they are Bitcoin,world Currency Will be.
I have the same opinion as you though Bitcoin is not the world's currency but its presence in the nation is now huge in terms of quantity and value. In addition to the barriers of governments to limit the influence of Bitcoin but most people around the world know about it and are dealing with it. That also shows it's global because it only lacks government recognition in that country.