Yes, there is still a need for fiat currency because not all people use bitcoin although crypto market have legal by government, many people only know with cash money and fiat currency, they do not know whit digital currency like bitcoin, maybe they will move to bitcoin after know benefit of bitcoin for people by no have inflation value like money could change value every day, after have crypto as currency we still need fiat for deposit bitcoin to bank and cash out money.
Fiat currency will hard to be replaced as long as crypto currency not supported by government. if government don't announce of using crypto currency, fiat will still remain. crypto has a lot of potential and benefits. but, I think locals will have difficulty to use crypto as much as their locations would not accept it much. in future maybe, everyone can accept it.