My problem w/ this scheme, if in fact it exists, is that it seems rather short sighted of Charles. It may be his personal desire based on his and Camilla's preference for the smaller Birkhall - but who knows what the future will bring, does he really want to forever give Balmoral away - depriving Prince George and his children of part of their heritage? What of when William is King perhaps he will want to host his brother and favorite cousins and their families at Balmoral, after all William and Catherine attended college in Scotland. Is Charles' goal to leave no personal real property to his heir and descendants?
Didn't George VI have to buy back Edward VIII's interest in Balmoral at great personal expense to avoid having the estate leave the main line of the Royals? What has changed since then that makes jettisoning the estate a good idea now?
I suppose since Balmoral is the Queen's personal estate she could leave Charles a life estate in Balmoral w/ the remainder to William when he becomes King thereby depriving Charles of the ability to give the estate away.