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.
There is room for many instruments on the financial market. I also think that fiat money will never disappear. There will always be someone who will be more comfortable paying with credit card, fiat or Bitcoin.
Everyone will cut their piece of cake and we will wait for a new payment technology .. maybe a chip under the skin? Who knows..