Would a country whose currency isn't worth the paper it's printed on have the infrastructure to use BTC? Would they be able to afford the transaction fees?
BTC would really need the support of a developed government, but those governments aren't eager to give up control of their currency.
Not saying it will be Bitcoin. It could be Ethereum, or some other crypto with (very) low transaction fees.
I don't think Bitcoin is a currency anyway.
Building a crypto banking service that can be controlled through a phone (e.g. in Africa) should have tremendous value given the very high inflation in some countries there.
BTC would really need the support of a developed government, but those governments aren't eager to give up control of their currency.