I think that would depend on whose residence it was and if it was their primary residence. Given the close proximity to Windsor Castle proper, I cant imagine it being anyone but a family member. It really isnt that big (as far as royal residences go).
I know there was talk at one point if for some reason the queen pre-deceased the DOE, then he may move there. but I think that was just speculation. I dont really see a need for it to be in use at this time, other than what it is - a meeting place and some entertanining and some tours at various times of the year.
I think all of the major family members have towers in Windsor Castle for their own family time and William and Harry would in due time as well. And Andrew lives in Royal Lodge on the same propert, so the York Princesses are taken care of. Anne has taken care of her kids, Windsor is only 30 min away from London. unless it is cousin of the queen or something.