Last year was Marvel, this year was Star Wars, what big thing will be next year? Seeing what Lego Dimensions is doing with crossovers, I think a great direction would be play sets with plots involving the three realms (Disney, Marvel, Star Wars) interacting together. I'd buy one!
Personally, I want a return to Disney. There are so many potentially great playsets. Nightmare Before Christmas would be amazing, but Sleeping Beauty, Jungle Book and so many others lend themselves well to this style game. A Muppet playset would be great, and would go with the new TV show. A Mickey Mouse clubhouse playset for all the classic Disney characters seems like a no brainer (w/ Goofy and Pluto). I would imagine we will get yearly Star Wars playsets for the yearly Star Wars movie.
Edit: I shouldn't have said "return" to Disney, as the "Disney" sets have all been Pixar or live action. I want some classic Disney animation playsets.