Whatever the scenario might be, we'll all be using the real money forever. No change in it, because each and every user give importance to bitcoin as well other cryptocurrencies as an investment and as a alternate to the traditional fiat. Maybe in future when direct acceptance of cryptocurrency increase the need for real money might diminish, but won't goes off.
I think it will be a bit useless because we already know the answer, we live in a country and under state rules. and fiat or real money is owned by the government, of course they will require us to use it at any time even as technology advances, crypto will still be an option because rules and regulations prevail over everything