A massive scale back could save it (which would involve significant return of funds/estates to the state) and all but the immediate heirs cut loose.
Unfortunately Charles is much less smart/adept at reading the public mood than his mother. He’d never countenance it on the scale it needs to be done. Plus he feels he’s ‘owed it’ at this stage.
It’ll all fall apart very quickly once he takes charge. So many people conflate liking the Queen with supporting the monarchy. It’ll be a huge test.
I agree with a lot of this except I am not sure the Queen is that great at reading the public mood either tbh. Her strategy is often "do nothing and it will blow over". And of course "it" often does! It is often wise to pause, cogitate and take the long term view. However, to do nothing to substantially reform the RF over a reign of 69 years, to be dragged kicking and screaming in to tax reform, or opening up the castles for profit etc, seems to me to be lacking in foresight. From a perspective of when she was 30, in 1956, she may think she has made lots of reforms such as giving up the royal yacht, paying tax,having to raise money for renovations, slimming down the number of staff. But the problem is that that perspective still does not match up with a 2021 outlook.
And as pps have said, I think the pandemic has changed us and shown us what is important, and what is not. We found out that we could do without vacuous celebrities, designer clothes, royalty, and what we really value is health care workers, teachers, lorry drivers, courier drivers, infrastructure workers, and bin collectors.
Personally, and I don't mean this in a disrespectful manner as I have nothing against them personally, but I find the public celebration of the Royal Family's births and birthdays and jubilees to strike an "off" note nowadays and next year I would think it more appropriate to celebrate the end of the pandemic (if it is the end) rather than lots of money spent celebrating the Queen's 70 years on the throne. I am not saying she hasn't been dutiful, and I admire anyone who can still ride a horse in their 90s, but I think public & state celebrations should be more collective nowadays and not just focused around the monarch.