Despite Seasons, I'm speculating that could be the end of expansion packs.

Maybe a time machine ep where you could travel to different eras (not the future like in sims 3) like the ancient roman times, 1800's and 1920's!

I think a off the grid/farming pack could completely change how you'd play. It would be harder to keep Sims alive and everything would have to be made or produced by hand. I think that would be a new fun and challenging concept.

I'm sure people and devs have numerous of other original ideas of eps that can be done.