Prince Charles and Camilla subjected Princess Diana to extreme and sustained psychological abuse showing no care for her vulnerability or young age. They remain deeply unpopular and score consistently low in public opinion polls. It will be a disaster for the Monarchy if/when PC ascends to the throne.
Prince William and (commoner) Kate taking the throne in his place would be the Monarchy's best chance of survival, but this is unlikely to happen due to PC's selfishness and lack of care about public opinion.
HMTQ is a wonderful woman but has clearly had enough of the shenanigans of the rest of her family, who can blame her at her age. She is in mourning for her much-loved husband who was her rock. I do not blame her for effectively 'sticking her head in the sand'; what else can she do?
PA has long been known to be an entitled ars* and the Emily Maitlis interview was an unmitigated disaster in which he showed himself for the fool he is. Reason enough to motivate more people to join Republic.
Re. Harry and Meghan, I believe there is much more to their story than meets the eye. I am sure that she received some awful treatment at the hands of 'courtiers' and 'the men in grey', maybe not overt racism but definitely classism and unwelcoming treatment which she interpreted as dislike and reacted accordingly. I do not believe much of the 'leaked info.' depicting her as a bully, and see this type of smearing as typical of the Establishment when it is on the back foot.
Harry is clearly not the sharpest tool and definitely appears to have substance abuse issues, but I can understand his bitterness to a family which treated his chosen wife with such disdain and the media which monetise criticism of the pair to the point that his wife felt suicidal. I personally blame PC for abdicating responsibility for bringing up a vulnerable teenage boy who was grieving for his mother to idiots like Tiggy Legge Bourke, when the boy needed a consistent, loving and caring parent in dialogue with him. Harry is now a loose cannon and, quite frankly, I hope he does reveal the truth of growing up in the House of Windsor in order for us 'plebs' to see the full extent of its dysfunctionality.
The Republic hoardings are already going up in major UK cities, and I don't think there is much that can be done to stop the growth of this sentiment.
Possibly the sight of PW and Kate on the throne might save the Monarchy, but I wouldn't put money on it. Too much damage has been done, and AFAIAC, much of it is on Prince Charles.