I think the next pack will be a game pack around February that will be a wild card: it could be anything really, as this is when they seem to try out new things (JA, Strangerville). It could be one of the ideas people have suggested, or something entirely new that no one has guessed yet.
I think we will get our community vote/knitting stuff pack in the summer, around July or August (I'm still hoping it also includes sculpting, at least). And I think we will get another supernatural GP around Halloween... very likely Werewolves... although after the last community vote, it could also include elements from the haunting theme.
Now, as for expansion packs, I believe we will almost certainly get one in June and one in November. I don't feel confident enough to bet on what either will be, but my hope is that one will be related to farming and one will be related to vacations... perhaps with multiple destinations, a hotel system, etc. But I could also imagine one that is related to hobbies more generally, or something entirely new.
I suppose it's possible there could also be another stuff pack thrown into the mix somewhere during the year, possibly another corporate tie-in.