Game could have a reliance on what arcs you've completed in KS (good ending only) and open what starting point you want for the story (through the main menu); Hanako, Shizune, etc~
It could be their story leading from that transitonal stage of highschool to career/college/whatever; and how they overcome the ordeals of a less static life (without the security of highschool)
I guess it would be considered more of an expansion then a sequal; but I'd love to see their individual stories unfold beyond the "first major trial" - becuase sadly, life is never so simply as a 1-time fix and then happy ending, two people have to work hard togerther to make it last.

thats my hope; but thats also just the longing of a reader not willing to put down a finished book, too i soppose.
EDIT: touched it up abit (didnt like some wording)