I am not sure but I think that all the titles Prince Charles holds as Prince of Wales immediately devolve to the new Heir and (hopefully) PoW . . . William. Charles becomes HM the King and William, among other titles, will be the Duke of Cornwall which means Catherine will then hold that and all Camilla's other present titles?
This leaves us with HM Queen Consort or H? Princess Consort . . . I think.
Charles is currently the Prince of Wales and Earl of Chester, the Duke of Cornwall, the Duke of Rothesay, Earl of Carrick, Baron of Renfrew, Lord of the Isles, and Prince and Great Steward of Scotland.
None of these titles are hereditary in the traditional sense. They do not pass from father to son, they (mostly) pass from heir apparent to heir apparent.
- Prince of Wales is a title for the heir apparent. The Earl of Chester is linked to this title, as the Earl is always the PoW (since the 14th century)
- Prince and Great Steward of Scotland, Duke of Rothesay, Earl of Carrick, Lord of the Isles, nd Baron of Renfrew are all Scottish titles. With the exception of the Lord of the Isles, they're all titles for the heir apparent. Lord of the Isles is a title for the eldest male child of the monarch
- Duke of Cornwall is a title that automatically passes on to the monarch's eldest male child if he is the heir apparent
When Charles becomes king none of these titles will be his to use anymore - and therefore none will be his wife's to use by courtesy. The only person who will be able to use these titles (some automatically, and some when he's created as such) will be William. Catherine, by extension, will be able to use the titles that Camilla currently has access to.
The only title that the female consort of the monarch traditionally can use is Queen Consort. The monarch does have other titles and styles, it's just a debate of whether or not the consort has access to use their female equivalent.
The big titles/styles that Charles will have are King, Duke of Normandy, Lord of Mann, and Duke of Lancaster. With the exception of king/queen, the monarch has traditionally used the male equivalent of these other titles, regardless of the monarch's gender. So, the debate becomes a question of can Camilla be known as Duchess of Normandy (or Lancaster) or Lady of Mann instead of Queen.
The problem with Princess Consort is that none of the monarchy's titles are "Prince," therefore there is no princess title (yet) for Camilla to use instead. There's also the question of if she becomes Princess instead of Queen, does that mean that they're doing away with the Queen consort title? What precedent is it setting?
The one thing that I could think of is if they make Camilla a Princess in her own right (similar to Philip), and while she will hold the title of Queen Consort she uses the title of Princess instead because it is something that she holds in her own right, instead of by courtesy.
I kind of suspect that when the whole Princess Consort thing was first released it was done so without a realization of how much people were going to debate and obsess over it in the years to come.