I think we are going to see a strange mix of something like CrocoBaura suggested. High School, Hobbies, Bands and Romance sounds more like a GP, so I'm not sure, maybe they will do a mix of those and combine that with one of the worlds from SimguruFrost's survey.
I'm not sure that they should attempt doing a Mall in the sims4, they struggle with doing zones with elevations, limited amount of sims in the zone, the mall is going to look deserted, and not run well on lower end machines and the whole game don't have a lot of reasons for your sims to leave their home lot to go shopping.
I'm also not sure we will see generations, that sounds like something that would require them to update the game a lot from being the basic Project Olympus game that it was and Maxis don't seem to want to do that. It's probably going to be different, like the things in SimGuruFrost's survey but simpler.
I guess Farming is possible, but I thought that back in 2018 as well and they have still not done a Farming EP...