Thats why I said there would be something to differentiate them from Ogryns...
As for feral and alien thats pushing it, I'm trying to think of combos and most seem to be covered:
Combat, mob: Orks, Tyranids
Combat, MC: Tyranids
Combat, elite/mec: Eldar/Dark Eldar
Combat, special rules: Demons
Shooty, mob: Imperial Guard
Shooty, elite: Tau, Eldar
Shooty, special rules: Necrons
Combined, Mob: Orks/Space Wolves (the way I play them at least), ?
Combined, general: Marines
Combined, elite: Eldar
Combined, special rules: WH/DH, Chaos
We have mechanise, non-mechanised, deep striking combat, deep striking shooty (pod SM) , special rules for almost everything ranging from undead regeneration of Necrons to Sisters' faith... If there ever was a new 40K army it would either be really boring or have a really cool way to do battle- if there is a way of fighting I haven't thought of and that isn't filled by a set army I would love to know it...