In the end, isn't it just a coin without it's physical matter? BTC was famous, growing, invested on, and believed to replace fiat is because it isn't controlled by anyone, backed by the miners mining them, and is safe to say that no one could probably obtain ownership of them. Plus, once the mining era is done, BTC basically has a limited supply, avoiding the issue of inflation which is caused by the ability of the current fiat system to basically just keep printing money.

I'm not particularly sure how countries would even plan on letting their coins flow in the world, but I see no difference with the current fiat except that its a virtual currency. Plus, it lost its entire purpose the moment the government made them, since it's basically defined as being monitored by then.