The case is different in many countries, some states have a strong fiat currency, so the paper money will remain valuable as long as the government developing the economy in a better direction.
Once again, the case is different depends on the region, some countries have been utilizing digital transactions more than using cash. However, there are many countries still using cash on daily transactions.
The main reason for this difference is the technology development and adoption are different in every country.
But yeah, we are heading to digitalization transactions that gradually replace cash tradition.