by Anduin
Hard to say... I would guess that if they bring out a new expansion, it would definitely include new factions. They already brought us new units and mechanics for the base game and polished many things so the obvious decision would be to expand the game with options for a 5th and 6th player.However I doubt it will come in the near future. Remember that many other countries outside the US don't even have the Banners of War expansion localized yet.
I'd love to see the orcs and dwarfs even though these races are already so used up.
And I don't even want to know how they will implement them. Do they get the cardboard sheets from the revised edition? What will happen for the 1st edition owners? *shrug*