I bilieve that in the future crypto currency will not replace fiat money as mode of payments in the future. Why? Because this two currency have a unique combinations that make our life more secure and convenient transactions trough offline and online transactions.
1.Crypto currency is more secure and faster transactions than fiat money via long distance and transactions like sending money around the world crypto is fast, safe and more secure then fiat money in this case fiat money is not good and slow in long distance transactions.
2.Fiat money is more faster and more easier in hand to hanp, face to face transactions and offline transactions in this setuation crypto currency is not good.
This 2 reasons why crypto currency and fiat money will be a powerfull combination in the future.
I agree with what you say
however, fiat currency will not be replaced, because it is fundamentally like traditional transactions and many people who have not been able to receive crypto as a transaction tool. maybe it will take more than a decade. so maybe bitcoin or crypto can be received by all levels of society.