Personally I think OP question might have been can we make sure bitcoin is accepted as legal tender world wide because bitcoin is decentralized that it can be accepted by anyone in any country regardless of the country’s stands on bitcoin or cryptocurrency. But if the question first is about legal tender world wide I don’t see that as what we can do, it is the government that can actually effect this change, by making it a legal tender.

If the question is about it been central currency for trade been agreed by all countries then that’s one thing I don’t see the government actually doing because they have actually labeled bitcoin to be a threat to their currencies and they fear it will hinder its usage. Even though it is not like that to me though