Hmm interesting question.
I wonder if KP isn't too far away from Buckingham Palace for it to be likely for it to be logistically possible for William as King to commute from one to the other most days - outriders etc. Clarence House would make more sense if they don't want to live "above the shop" but maybe Camilla would still be there/have use of it.
Adelaide Cottage is of course very small, we know that. I guess they could still live there, there would be no immediate need to move out as it seems pretty secure, within the Windsor Castle security cordon etc. I suppose they'd also have use of Windsor Castle so could travel "up the hill" when they need to use anything more "regal". Windsor Castle is quite open in terms of public access which again may put them off moving in there with the kids.
With Anmer there would be no immediate need to move out. TBH I imagine they could still use Anmer and then open Sandringham at Christmas for the traditional family gathering - maybe even staying at Anmer and just allowing the family to use the main house.
I guess part of it depends on how wedded they are to their residences - Adelaide is the newest so in some ways they may have the least ties to it and be more willing to move out to Windsor Castle itself (I mean practically Royal Lodge or Frogmore would be more private for a family). Anmer was one of their first homes - a wedding gift - so I'd suspect they have stronger ties to it. But maybe they'd be happy to move in to the "Big House". They don't seem that tied to their KP apartment - they've happily not used it for some time now since moving to Windsor but then again they may feel its the best, most private, most emotive/connected for them London residence.
I don't think they'll make their main home in London, Windsor is more likely IMO. The question is just which residence - if they could secure some more privacy then the Castle itself might be logistically easier.
Here are my thoughts on what might happen to homes for the Wales family if William were to become King in the next 5 years or so.
> BP remains the "shop". They may choose to move there if they can carve out a nice family apartment there, else, they will hold onto KP1, which will continue to be their London home.
> Clarence House: I do not believe William will use Clarence House. It could continue to be used by Camilla, and in time, George could probably take it over.
> Windsor Castle becomes their main home. The family move in there. No changes to schooling as a result of the move.
> Adelaide Cottage: No longer to be used by William & family. Perhaps Andrew might want to take it on.
> Anmer: Remains their main home on the Sandringham estate, they appear to love it. The main house will be opened up a few times a year, but that is about it.
> Balmoral: As is currently the case, will be used for a limited period by the family over the summer, but be open to the public for the rest of the year
> Birkhall: Tricky. Camilla probably loves it, but William will probably want the house for his family. Perhaps he will let Camilla keep it for the rest of her time, and William will end up using Craigowan Logge or another building on the estate.