I wonder how Rockstar will get away with a Bully sequel in the current social-political climate we live in. A game in this day and age where we play as a teenager who beats up not only other teenagers, but also kids and adults, would give politicians and sjws a field day, they would certainly try to ban it for inciting violence in schools. I remember that Bully raised a lot of concern before release, and many countries tried to ban it. So I think that a sequel with far more realistic graphics, details and gameplay mechanics, will probably raise even more attention.
The casting call leak suggests that it is a direct sequel, where Jimmy Hopkins is in college. So he is over 18 now.