I agree that too many sub forums might fragment readers and have a negative impact on discussion. Maybe separate it out by type of media?
-Star Wars Movies & TV
-Video Games
-Theme Parks & Exhibits
-Novels & Comics
-Theatrical Cuts vs. Re-releases
-Toys & Memorobilia
You could make a solid argument for splitting some of those into separate categories (especially movies and TV), but I think there’s enough overlap to justify keeping them together. It’ll be hard to talk about, say, the Cassian show without also talking about Rogue One.