I think another question to complement the thread is whether there's a country whose infrastructure is ready to take up cryptocurrency.
Rural areas with no internet connection is a challenge to implement crypto. I can't imagine how my kid would ran errands to buy something for me from a mom and pop store.
If people can think of a feasible solution to this, then we should see in the near future crypto replacing fiat national currency.
Adoption should begin with the masses - fishermen selling their haul for the day, vendor selling fish in the market.
In areas where there's little or no internet or electricity, surely sealed recyclable tokens containing Bitcoin private keys of various amounts could be used and distributed? Different shapes and colors could be made depending on value, so that different values can be recognised as easily as is the case with national currency. If you wanted to spend a token online, you'd simply break the seal and use the private key.
I believe physical Bitcoins would improve the utility of the currency. It would enable more transactions in person where internet, electricity or technology is scarce, and create a monetary connection between those places, and the places where Bitcoin is used.