I wonder about a wife for Gloucester in this scenario - a "whoever does not get Jamie"? Though Sophia Dorothea is unlikely - William's mom disliked House of Hannover. And while Willam III would like to "Dutch'ify" the House of Stuart as much as possible (having no shortage of first cousins once removed) I'd like for future Duchess of Gloucester to be not Dutch.
Aha that is true, hmm, if there's a Protestant Princess available from say Saxe Coburg Gotha, that could work?