No word on any other human kingdoms. Cathay was confirmed in the very first trailer for WH3 so its no big surprise that they showed up. Its just the content for it that is so surprising. I am willing to bet Ogre Kingdoms will probably be around (in WH2, you can hire some Ogre Mercenaries after the latest DLC so an army of them may not be too far off) and many people are still holding out for Chaos Dwarfs. I wouldn't be surprised if we saw Middenheim, Lahmia, and Nagash at some point since they have been alluded to in updates in WH2 but nothing concrete has been announced.