How much more content are they going to add?

Yeah, they really can release as much as they want so long as it makes money. They honestly did not spin off the legacy version until fairly recently and it seems to be making plenty of money, too, so I do not see much holding them back.

If you are wondering if ideas would limit them, I highly doubt it. Considering the piece by piece nature of the game anyway, it will not take much to think of another piece to add. Just look at the forums to see all the packs people still want or even past content. There are plenty more occult that could use a GP, plenty of pets/animals that could be added, plenty more vacation destination GPs possible, and that is not even including all the million stuff packs they could do especially if every hobby qualifies. EPs are slightly more complicated, but I don't think by much considering. I imagine some social and/or family EPs would be easy ones.