Indeed. Making the Tron World as Ansem's main computer information system was a very clever way of fitting it into the KH universe. Merlin watches over Pooh's book as well. Not as clever, but it still works rather well. Hollow Bastion will definitely be in KH 3D, or else Square Enix is stupid. Plus, everyone like it.
My sister says that the Tron world (Paranoid Space) is crap and stupid. She just can't handle the fact that there are TWO other worlds in Hollow Bastion/Radiant Garden. For KH 3D, the maker said he'll be having some old worlds, as well as new ones as well.