I don't get the feeling from H&M that it matters to them to keep the connection with the RF intact (if they are, they are going about in a very peculiar way), but i will change my mind if the content of podcasts, interviews and books will drastically change over the next time.
if i were K.Charles, i wouldn't change anything concerning to the Sussexes, no stripping of titles, letting them keep the titles and styles they have now due to the Letters patent in 1917.
But make a very clear statement in general that taxpayers money and organised security are only given to working royals, this is no surprise nor change to any of the other family members.
Then in private have a business meeting with the Sussexes (not just an informal chat), to make them understand when and in what situation security and money is giving to them and when they have to arrange it themselves, and make them very clear (and have them sign something to confirm their understanding) that these are not related to whatever titles they may have.
...and for any public complaints H&M will come up with in the future stick with "recollections may vary" and "are house is always open to discuss the matter in private"
Their links to the royals is all they really have to make money. Ether that extends to wanting the children to have titles is another thing.
Harry and Meghan should get on with living amd any child’s title is really beside the point as would say.