Personally, I think that bitcoin won't become a new world currency like USD or EURO, but I think it would be widely accepted and used. But looking at some projects like El Salvador I just keep wondering, are there gonna be countries that will try making bitcoin their official currency and make all transactions using it?
It will be difficult for countries to just make bitcoins their official currency since they will be unable to make modifications to it. Countries may in the future agree and accept bitcoins but they will never formerly make it their official currency since it was not created by them. Consider this example- Imagine a sovereign country that has no relationship with the United States just deciding to accept the US dollars as their official currency without trying to name it after their country or at least make some modifications to it. What most people into bitcoin are aiming and hoping for is that it gets accepted for use in their country, even if not as the major currency for payment , but as an option.