It is definitely being made. Console hasn't been announced although I suspect it'll be on a PS system. Whether that would be 3 or 4 depends on how long Nomura takes to finish Versus XIII and crack on with KH.
As for the worlds, I'd like to see some more modern Disney worlds (Princess and the Frog?) and some older ones such as Lady and the Tramp or Jungle Book. Especially Jungle Book.