i haven't seen it directly, but CA has apparently confirmed that their long-term plan encompasses all of the fifteen 8E army books plus Chaos Dwarfs... and may go further. A lot of people are pushing for them to also include some of the human factions that GW didn't do and which are nevertheless on the current campaign map or will be on the mega campaign map - Kislev, Tilea, Estalia and the Border Princes currently use Empire units, and there's a good chance Araby will be in the megacampaign map when it lands. (Note that one could say that the Dogs of War list could be considered to be representative of Tilea, and to a lesser extent Estalia and the Border Princes, and there was at least a partial list for Kislev published in White Dwarf during 6E - there are no indications of whether CA will use any of these, however, and they've indicated that they want to do the core army book factions first.)
There was also a datamine before any of the DLCs landed, which had the following information:
DLC3: Beastmen (done)
DLC5: Wood Elves (done)
DLC8: Tomb Kings
DLC13: Chaos Dwarfs
DLC15: Ogre Kingdoms
Game 2: Dark Elves, High Elves, Lizardmen
Game 3: Khorne, Tzeentch, Slaanesh, Nurgle
(Note that Bretonnia has been released as FLC, so the currently released factions are Empire, Dwarfs, O&G, VC, WoC, Beastmen, WE, Bretonnia)
CA's response to the datamine is that it's out of date, and plans have changed since - however, they've also indicated that their plans have expanded in scope (TW:WH did better than expected, so they're putting more resources into it). An initial effect of this seems to be that they're putting Skaven into game 2 directly rather than having them as DLC. A lot of people have also questioned whether they're really going to stick to a 'four flavours of Chaos' model for game 3, since such a model may have little to interest people who aren't Chaos fans. Certainly, though, it does look like Chaos Dwarfs are going to be in - eventually - one way or another. On the other hand, a lot of people think that Tomb Kings will be introduced before game 3 (they do occupy what would be a strategic location for the megacampaign) - which means that they'd have to do something unexpected to get four races for game 3. (This could, however, mean doing WoC properly: what's currently in-game is essentially a filler because they had to have a northern Chaos invasion of some form.)
One other thing to note, speaking of the datamine... the datamine also came with a world map showing Ulthuan and the New World being significantly shrunk compared to the Old World. By that, I'm meaning Ulthuan being about the size of, if not smaller than, Bretonnia, and the entire region being about two-thirds the size of the Old World. I'm pretty sure that map is out of date (and possibly merely a filler all along), but do be prepared for some pretty major distortions in scale.
TL:DR Unless plans change, Chaos Dwarfs will be in... eventually. May be game 2 DLC, may be game 3, may be game 3 DLC.