From http://forum.eternalcrusade.com/threads/the-first-foundings-q-a.1027/ Will Plague Marines, Noise Marines, Bezerkers, or Thousand Sons make an appearance? Yes, for sure, but most likely in a post-launch update. we may not get the World Eaters, Death Guard, 1KSons or Emperors Children but we will get the cult troops at some point
The problem here is that this appears to be the suggestion of Garrett Fuller (the article author) and not a statement by anyone from BE, he is expressing how he thinks it should work, that's why the paragraph starts with 'I' inferring himself as the author, and not something like: "Behaviour has talked about..." or something to that effect as the 2nd to last paragraph starts.
Honestly ill play all the chaos god aligned factions just because I like to have a variety of characters to choose from if the berserker doesn't chow im most likely going to go sorc for thousand sons or chaos raptor
Well remember that the Black Legion has Khornate Bezerkers from the World Eaters Legion in it's menagerie, as well as Death Guard and probably some Emperors Children (Thousand Sons probably not since they're all-minus the psykers- y'know dust....) so you may be able to play a bezerker if you select black legion.
I'm sure we'll get the rest of the Traitor legions at some point they probably just want to make sure people are gonna play the game plus the "Cult" Legions get enough love in other media so they probably wanna give the not as necessarily popular ones more exposure
If World Eaters should ever be playable, they should have a friendly fire option on. because you know, those berserkers are just as likely to turn on their own brothers as much as the enemy!