I found this expression on the news channel about the crypto currency: "Anyone who will try to buy coffee for cash in 2023, runs the risk of causing laughter from the seller, that he does not use crypto currency."
how do you think, is it realistic? Can a crypto currency replace national money?
I think that it's possible, but it will take more time.
South Korea has already launched their very own centralized cryptocurrency known as "S coin". A cryptpcurrency developed for use in investment matters by the people of Korea, if this coin thrived in their local market, it may be able to replace their fiat money in the long run. However, that's not the case I think for decentralized coins like bitcoin.