Bitcoin at its current state is not scalable for worldwide usage. Moreover, Central Banks wouldn't let some random currency to take over in near future (I'm not saying it won't happen at the end) and until then I am 100% sure that there will be not just one but many different currencies and all of them will be equally valid. I see a future with tokenized asset instead of money, tokenized wheat, tokenized butter even tokenized houses that you can exchange 1-1 instead of putting money into the equation.

Money was invented because it was hard for people to trade 1 tonnes of carrots for a horse cart, now we have the technology for that, a facility can provide the storage and issue some amount of tokens for the carrots, that person can then sell those tokens to businesses for goods and other tokens, and businesses can claim those carrots later on.