>>712400975
Loyalist muhreens (definitely smurfs and blood angels, maybe fists, maybe wolves, possibly dark angels)
Chaos muhreens (death guard, world eaters, maybe thousand sons, maybe emp's children)
Guard (probably going to be split up on factional leaders but Cadia and Krieg will definitely be represented somehow)
Orks (different kinds of bosses: a normal one, a weirdboy and a mekboy probably, maybe a gretchin)
Eldar (don't care enough to list them)
MAYBE T'au but I doubt it
Deldar will almost certainly be an early DLC faction with a homunculus leader and some mechanics like clan moulder to create nasty shit
Nids will come later and will definitely have a whole DLC mechanic centered around them with reproduction, razing worlds, etc; gonna be hard to get them balanced
If T'au aren't in at launch they'll get a couple DLCs (assuming the first doesn't sell like shit).
They probably won't be in at launch but we'll likely get an Ecclesiarchy DLC later that adds them as a Guard faction with unique SoB and maybe assassin units. They don't have the manpower to be their own faction.
Mechanicus will probably get their own faction entirely later on in a DLC, possibly multiple.
Pure chaos (ie, not muhreens) will likely get DLC later as well, but if they're planning on doing multiple games then they're definitely getting saved for 2.
Obviously the launch factions will get expansions, we'll probably have every muhreen legion represented by the time the game(s) are finished.