I hope the stage kit still works with future games; I only just got one myself. It would surprise me if it didn't, especially considering it works with RBN. At the very least I would expect the lights will continue to work, and maybe not the smoke part.
Anyway, this is the only thing I could find:
I guess we'll find out when GD:RB is released. If that supports it, I cannot see why RB3 wouldn't. Although it would be nice if we could get some official confirmation as they now have announced future titles.Harmonix has confirmed to our pals over at Joystiq that a compatibility patch won't ever be produced for TB:RB, and when pressed about compatibility with future titles, the rep simply stated that the company "hasn't announced any future titles at this time." Looks like this party's over, folks.