After a great deal of thinking, I've come to the conclusion that the core races of TW:W3 will be Ogre Kingdoms, Chaos Dwarfs, Daemons of Chaos and Warriors of Chaos. Yes you read that right, a race we already have.
"But we already have WoC, they can't sell it again!"
Quite right, they can't. That'd be a real foolish and jerk move. They can however, give a discount equal to the the full price of the WoC DLC to purchasers of the game that already own the WoC DLC. Similarly if for some reason, someone does not already have the WoC DLC when they go to buy be 3, they would not receive a discount but would have said DLC given in addition for free. Think of Blood for the Blood God 1 and 2 here.
By using them as a headliner, they have less to work on overall, which means refining and implanting superior mechanics for a lackluster race, and even more exciting: adding the missing half of the WoC roster and more LLs. Skullcrushers, Hellstriders, Chaos Warshrine, Slaughterbrute, Mutalith Vortex Beast, Chaos Ogres; the Lores of Tzeentch, Nurgle and Slaanesh; and Valkia the Bloody, Vilitch the Curseling and Festus the Leechlord to give us one WoC LL for each god!
This leaves Kislev as a clear option for a race pack, alongside the possibilities of the Hobgoblins and Cathay perhaps. The OK vs CD as a lord pack and a WoC vs DoC lord pack as well.
The reasoning behind this idea? We weren't supposed to get a playable WoC faction with Warhammer 1, they were just going to be the end game boss. But folks demanded them now and they caved, which is why we have them in a very unfinished state. It is extremely likely that game three was meant to be their time to shine, which it still can be given the lack of remaining races to headline with, and this opportunity to do them right.
Tomes read: The Great Betrayal, Master of Dragons, Curse of the Phoenix Crown, Trollslayer, Skavenslayer, Daemonslayer, Dragonslayer, Beastslayer, Vampireslayer, Malekith, The Bloody Handed, Shadow King
It's T. rex, not T-Rex, you filthy casuals.
"Draconic murder ferret attack dog." - Ben1990 describing Shard Dragons.