Most likely, all countries will really switch to cryptocurrencies, but not the cryptocurrencies we all want, because many countries are working on creating their own cryptocurrencies. I doubt that, for example, all countries will legalize Bitcoin in the near future, but I believe that this will happen in the longer term. Perhaps in addition to BTC, other cryptocurrencies will be legalized, for example, such as ETH, XRP, XLM, TRX and others.
Cryptocurrency has an indefinite status in many countries, but in most it is legal, even if it does not have a legal status.
If everyone switches to cryptocurrency, then the already extremely manipulative world political field will turn into a battlefield, where the main weapon is the manipulation of cryptocurrency rates.
Rather, then everyone will create their own stable coins, which will not differ from ordinary national currencies.