No, the cryptocurrency is simply not capable of replacing the national money of the states. Individual citizens can completely switch to the use of cryptocurrency, if they have it, of course. However, no state will ever give up their national money in favor of a decentralized cryptocurrency. This will quickly lead to the unbalancing of the economy of any strong state, since the decentralized cryptocurrency actually has no relationship with the economy of any state.
When there will be a single world government on Earth, only then fiat can be replaced with a cryptocurrency, and that, subject to the availability of a certain level of technical progress and a high level of incomes of citizens.