I thing in the future most of the world will use crypto currency but when the time comes.. you can see how the evrething evolved for 20years
Most likely, in the near future, the national digital currency, which will be in circulation in each country, will become widely distributed among the population. But for its introduction into circulation, the society must be prepared technically. To do this, the Internet must be available anywhere, and everyone must have a smartphone.
And to be honest not everyone has a smart phone or is prepared technically. Like me, a developer who hasn't purely understand bitcoin yet...