Well, they will all be in the game, it is more "which will be playable on release". Then again, you will have mods after a couple of days unlocking all the factions, so it isn't that much of a big deal.

I think the Germans might get the cut, they are not an unified power in any sort of the word, this is why Rome failed to take the areas, there was nothing to plant a flag in and say "We own this area".