To be fair, all Allied Races are simply sub-races. And all races but Gnomes, Worgens, Undead and Goblins have got them. Mechagnomes are indeed obvious because it's either them or leper gnomes (which would make absolutely no sense). For Goblins, it could be either Vulpera or Gilgoblins, because they are based on the Goblin model. Although, logically, I agree that Vulpera are 1. more desired and 2. simply make more sense since Gilgoblins are known to be purely hostile before BFA. Touching on sub-races though, there has been a lot of speculation of the "Lightforged Undead" or whatever they might be called, that would be lead by Calia Menethil (This has been touched on by Taliesin and Evitel). Although for Worgen, there are no likely candidates for the race.