Horses aren't officially confirmed, though it does appear they're likely to be arriving. I'm still going to include them on my list of wants.
Hotels - in several styles. Would love a modern/casino type of look, something rustic (I know we have outdoor retreat already so not exactly like that) and something beachside.
Hobbies - like Freetime with several different paths to follow. Music: giving us more musical instruments: Sculpting: which can include things like pottery, woodworking, metal working, glass blowing: and something else, I'd prefer something fitness related but that's not as likely.
Horses - for pets but also for showings
Medieval themed pack. Though with the castle content likely winning the vote for build buy, and the horses probably coming, I think this is now unlikely, but that doesn't mean I still can't wish for it.
Egyptian themed world, as a non-residential world, pyramids and treasure to explore, and also Mummies!
I'd love some more retro/decades items, even if just decorative. I'll take anything like this for build/buy but am more choosy on CAS items.
Anything that's a similar style to Sims 3 Bayside. Still my favorite theme the series has ever had.
More activities and items for pools. Also things for casinos. But much of this could be included in with a hotel EP.
Since I think something amusement park would not be something we'd get - see the Ferris Wheel as a rabbit hole - and zoos and aquariums are a bit too much of a theme to really represent in the game, I think if we got all of the above I'd be 100% happy.