Yes l agree with you mate we can not totally eliminate Fiat currency from financial transactions despite the world is turning to a global village where digital currency will serve as means of transactions the usefulness of Fiat currency can not be under rate. There are still people who don't speak or write or even know the internet of things, these set of people are the once we some time buy raw materials from in the manufacturing industries and other sectors as well ,because of their inability to computer or phones they will prepare transaction such as the physical Fiat currency they can see and this might slow than the rate of production in businesses.
My suggestion:
these people should be more educated and teach on how to use the crypto currency as a fastest means of transactions in their dealings. If this is address and achieve the crypto currency will result heavy mass adoption.
Yes definitely we should not totally eliminated the fiat currency because huge amount of people in the world still use the Fiat currency for the day to day transactions.Many have not even heard about the cryptocurrencies and only depend upon is the fiat currency.Fiat has been established from the traditional time period and also the government supports it more than the cryptocurrencies.Cryptos cannot be operated everywhere as they require internet connection which is not available everywhere.