I'm sure bitcoin must be able to dominate the world. all countries will use bitcoin as a legitimate transaction tool. but despite that. the world still will not be separated from paper money. because paper money can be made as a symbol or a sign of the country.
One of Bitcoin's main principles is that there are no borders it has to respect or abide by. It's one protocol that has no equal, and one that at the same time can't be stopped. It's pointless to focus on what paper money will be like by that time, we should only care about what matters for us, and that's slowly taking distance from dealing with fiat. Let countries have their paper money, we have Bitcoin, that's more than enough. In current times it requires only our smartphone to transact with others or buy our daily needs in stores. I could perfectly use Bitcoin as sole currency if it enjoyed more adoption and stability. Fiat is a mixture of state and corporation money, while Bitcoin is people's (everyone's) money.