It is remarkable how much the Queen's standing has improved during the time since that song (1977). My (UK) family are (as far as I know) staunch republicans, but the last couple of decades have seen all of us soften our disgust with the monarchy as Elizabeth represented it. We might still want the whole concept destroyed, but there is nothing close to the vehemence of Johnny Rotten (Lydon)'s lyrics from that song.
Nevertheless, that is how a bunch of people felt in 1977, and as our memories become even more gilded and rose goggled now that she has died, it may be worth remembering those feelings too:
God save the queen / The fascist regime / They made you a moron / A potential H bomb / God save the queen / She's not a human being / and There's no future / And England's dreaming
These days, I think even us staunch republicans/anti-monarchists would begrudgingly admit that "She could have been worse" and that she actually was a human being.
Maybe Charles will have the guts to end it all, but it doesn't seem likely.
Be very careful what you wish for. As a French, living under the rule of an elected monarch who changes often, but doesn't answer to anyone during their reign, there is something extraordinary to see the British PM bow to the Queen, and do that (I think?) every week.
At the same time, if the monarch (in a system like that of Britain) actually started using and abusing their theoretical powers, they'd quickly have the whole of the country turn against them. And they have a lot to lose if that happens!
In a presidential system, the President is both the theoretical and actual head of state. They're already in the top spot, and the only thing preventing them from staying there is convention or laws which are subject to change, and enforcement of which is largely under the President's control.
A more ceremonial President might work as well, but the thing is, an elected head of state has less to lose by abusing his powers, and far more to lose by properly following convention and thus stepping down.