So in a governments aim to control our money it will leave a big opening for bitcoin and other decentralised crypto to exist along with fiat and will allow people to "trade" anonymously with each other over a completely independent infrastructure.
Bitcoin is examples of open cryptocurrencies. Everyone can see how much money you have on your wallets, how much it you send and who gets this money.
Technically we cannot know who is holding that wallet which mean we are really anonymous but in terms of security we are not because of KYC. Fiat money is very important because not all people knows how to use cryptocurrency but I think our future with cryptocurrency is pretty amazing.