I'm not really sure about that. If that would be a central currency I'm sure that many people will use it and use it in illegal ways like private transaction or anonymous transaction and money laundering I don't think all the governments would not agree to let this happen, I'm not really sure about the consequences but I'm sure that it's impossible to happen right now.
Its hard to think that it will happen while the fact is even even dollar didn't succeed to be the 1 world currency even if how rich this country is and how strong tge law they have so maybe the idea of bitcoin to go thru that far is so impossible maybe for now we should enjoy the benefits of having bircoing on our pockets.