I seriously doubt H&M will come back as working royals. They are not even remotely trustworthy, I imagine the security services have been monitoring their activities, and I don't think the British public will want to have much to do with them. I just cannot see Meghan wanting to return under any circumstances.
Harry (and his children) being able to see Charles should the worst happen is another story. That's a personal, family matter, and if that's what Charles wants, even if Harry is not doing anything to apologise or seek forgiveness for all of his vileness of the last 5 years, then that really is up to Charles. That goes for his funeral as well. At least Harry cannot complain that Camilla/Catherine/William kept him away from his father in his dying days. Harry's complaints about his life need to end with Charles. William is and never was responsible for his brother's upbringing and childhood experiences. If William can take up the throne without the hangover of Harry's issues with the previous generations, I think that can only be a good thing.
I am not naive enough to think the attacks on William and Catherine won't continue, not to mention their squad starting on the children. But if it does it will be based in pure spite and envy, not fueled by a perceived injustice over Charles's last days.
WRT AN Wilson, his tongue is always firmly in his cheek. He likened Spare to Mein Kampf after all!