bitcoin could be the world's currency, but maybe not.
In my opinion, Bitcoin has great potential to become a world currency, but it's just that many countries still don't legalize Bitcoin and other cryptocurrencies, from this reason it becomes a bit of a serious problem in adjusting Bitcoin to become a world currency, but I see that many countries have accepted Bitcoin, there are also countries that must first exchange it for local money and there are also several countries that do not need to exchange it for local money.
I have the opposite view, bitcoin has no potential to become the world currency because of its decentralization. The government will never let that happen unless they figure out how to control it.
El Salvador recognizes it as legal tender, meaning using it as an official currency since they do not have their own currency, they are using USD and accepting bitcoin as part of their economic recovery plan. For countries with strong local currencies, like the US or China, they have no reason to give up their currency for something they can't control. There is no way for bitcoin to become the world currency.
El Salvador's future since becoming a legal tender is still a mystery, they are still on the experimental stage and its outcome is not yet confirmed. Other countries or places in the United Arab Emirates, Kingdom of Saudi Arabia and Singapore is also looking forward to become one of the legal tender but they just cannot fathom the risks for now and chose to observe El Salvador's outcome first before taking a huge leap.
And for the bitcoin to become the world currency is not yet possible in the next decades to come and I reckon that it's not also created to be like that. Just like what you've said, the governments of each respective countries aren't going to allow that to happen as there's no way that they can control it as it's also not designed to be controlled.