in my opinion, all goverment currency will be stable coin, and must be stable coin 1 = 1 with national currency, but if the rate of national currency fail, the coin price will be fail too.
ofcourse all people must use it, but people still have other option like the booming of e-money right now. people can use national e-money or other option.
and i think the regulation will not come easily, goverment will use "private blockchain" like IBM service, goverment still afraid with super computing computer where can crack private key easily from public key ( of course this issue not happen right now)