I really think Cannonball should have his own team of X-men.
I would think he would have been a great fit to take over Wolverine's role as leader of the Astonishing team, but since that book and X-factor are both ending, it might be cool to see him reunited with some of his former New Mutants/X-force teammates as an actual X-men team.
Or if he lead a team of New X-men characters, which I'd like to see get their own book anyway. It would be cool to see him actually be the senior member of an X-men team, so this could be a great two birds with one stone type scenario; Cannonball could finally be on the X-men as the leader rather than the junior member, and the New X-men could get some leadership that genuinely understands their perspective somewhat.
Or, barring either of those options, I'd have him on Storm's team, so at least he wouldn't be the youngest character.