The question here is not faith in paper money. Paper money, ideally, is printed according to the volume of goods and services that can be purchased and that are provided in this state, that is, they are directly related to the economy of the state. Cashless payments in the national currency and the digitized national currency are also associated with the economy of the state, which cannot be said about the decentralized cryptocurrency.
In addition, paper money is the least tracked by government authorities, as opposed to digital currencies, with the exception of cryptocurrencies. Therefore, it is not worth giving up paper money, and this issue will be completely decided by states and their governments.