For cryptocurrency to replace fiat, you need an appropriate government decision. However, no government will ever abandon its national money and switch to the use of cryptocurrency, which is not able to work so closely with the state’s economy as its usual currency. Cryptocurrency for any state is alien and no man's, that is, not only not secured by anything, but also not having the authority of a particular state or group of states, as is the case in other currencies. Therefore, no state will take such a risk, it is much easier for them to issue their stable coin or use other stable coins.