There is supposed to be a KH release on the Wii, if I recall correctly. It is going to be a rehash of I & II made for the Wii. It was announced at E3 or some other gaming conference this year, I think.

Not only does the KH team have to finish with Birth by Sleep and Coded, if I am right about the Wii version of I & II they'll have that to port to the Wii too. Also, if I recall correctly, part of the KH team is working on FF vXIII and that's not done either. So I think we'd have to wait at least another year or more until more progress has been done with Versus before we even get a smell of a true sequel to the series.