I’d love a Warhammer 40k theme. Huge amount of lore, art, and fanbase to work with. And Games Workshop is definitely open to licensing based on the number of console/pc games, Funko pop’s, books, ad nauseum. Hell, they just struck a deal with Marvel for a graphic novel series.
And my god the number of main chapters of Space Marines they could do limited editions of. Not to mention all the other races in the game.