Too Long; Didn't Read
Since the advent of Bitcoin and altcoins, each year that passes brings with it a slew of rumours and leaks regarding the development of national cryptocurrencies — public blockchains designed for use in a single country, alongside or potentially even replacing the fiat currency in question. There are two ways this could theoretically happen: independent developers create a currency which becomes so popular a government adopts it, or the government in question researches and develops a currency of their own. The latter has happened already in one case, albeit without much in the way of results thus far. It is worth mentioning that although these currencies can be stablecoins — tokens pegged 1:1 with the fiat currency they are linked to — this is not a requirement. Similarly, many stablecoins exist that are not national cryptos.