I think that paper money will never disappear. No government will want to completely switch to the digital currency, as this will bring chaos to the economy of the country. Now the material value in each country is determined by the annual gross income and gold stock. Proceeding from this, the country's economy is being built, a certain amount of paper money is printed. What to build an economy, if you switch to a digital currency?
I think paper money is very likely to disappear, what can replace paper money is digital money, digital money is certainly easier to control because the government has full access compared to paper money.