Cult of Ulric is still Empire faction, but with special units. Kislev is more of its own faction(same goes to Cathay, Ind and Nippon).

As for game three while I agree that better option will be ME something tells me that ca will add another standalone campaign and I hope that it will include far east factions because destroying dark lands won't be that fun. I want some order oriental stuff with awesome oriental units like serpent dragons, monkey warriors, terracotta warriors.... all does things are in Cathay lore and its much more fun destroying Cathay and Nippon as Chaos than Chaos dwarfs or Ogres who are as messy and sadistic as Chaos.