of the options given, Chaos Dwarves, Demons, Ogres, Kislev, and Dogs of War all had armybooks at one point, and thus extant material to use as a base in creating a faction.
Araby, Ind, Nippon, and Cathay never saw any official coverage, so the total war team would have to invent all the details whole cloth. which is something i can't see GW allowing. the Old World might now be "the world that was" and the Age of Sigmarine at hand, but they always have the option of returning to the Old World for a product (or game revival) or bringing a bit more of the Old World into AoS, and i don't think they'd want to give a computer game company the power to dictate faction designs.
of the ones with extant armybooks, i'd say that Chaos Dwarves or Ogres are most likely. Kislev always seems to lumped under The Empire, even if the official status was one of an allied kingdom rather than a component state. so if Kislev is added it would probably be as a variant Empire sub-faction. Demons, while certainly a core part of the narrative of the Old World, don;t really seem to operate with the same kind of nation-building system that the other races use, so they would be really difficult to make a playable faction in campaign mode. the same goes for Dogs of War.. while technically Tilean when fielded as a full army, they are basically just unique mercenary bands that usually deploy alongside one of the other factions. so if added they'd best be done as unique hireable units meant to bolster your normal armies.