If they want to step back, step down, take a lesser role or whatever that is up to them. It's definitely true that as we move on, Charles becomes King and William's kids get older, Harry is a lot less relevant. Making the split now avoids a situation like Andrew's in that he's a spare part with no clear role and seen as a waste of space.
BUT. You can't do all of that and keep your royal status. It does seem very much that they want all the good bits of being Royal like the houses and titles and publicity, without any of the negatives. Yes you can go off to Canada, raise your kids there and host a chat show. But as Meghan Sussex and Harry Sussex, not as the Duke and Duchess of Sussex.
I also agree with a lot of what's been said about a woman who is estranged from all of her natural family apart from her mother apparently doing the same to her husband.
How are you supposed to "split" time between the UK and Canada when you have a child in school? Popping back and forward might work for the first few years, but once Archie is 4 or 5 they will be looking to make one place their permanent home, and that will be Canada or LA. No doubt about it.