I really, really hope that they'll probably include all the ones mentioned in the trailer (men, dwarves, orcs, undead, chaos) - it'll seem a bit disingenuous if they don't. I'd imagine skaven and elves will be the DLC packs, as I doubt any other races are popular enough to warrant being DLC.
They are. Articles are mentioning that the developers confirmed Orcs and Goblins, Empire, Vampire Counts, Dwarves as being in the game. They haven't specifically mentioned Chaos but that a power in the north is gathering.
From Rock Paper Shotgun: "Initial details from publisher SEGA confirm the game will include the Empire (under Karl Franz), the Greenskins (under Grimgor Ironhide), the Dwarfs (under High King Thorgrim) and the Vampire Counts (under Mannfred von Carstien). Chaos, whether Tzeentch or not, isn’t mentioned by name, but it does say here that “a greater threat still whispers in the winds from the north. The fabric of reality itself begins to rend and buckle” so yeah, Chaos is in there too."
What are the other races? Bretonnia, Skaven, High Elves, Dark Elves, Wood Elves, Ogre Kingdoms, Lizardmen, Tomb Kings, Beastmen, possibly Khorne, Nurgle and Slaneesh.
The only unlikely factions I would think would be Chaos Dwarves, Kislev (unless they're added as part of the Empire), Border Princes and really distant ones like Nippon and Cathay. Though I think it all depends upon the scope of the campaign map. Will it be the Empire area (which all the factions confirmed are/can be located in) or will it extend further west and south?