Among the new rules rumors for the new edition, is opening up the force organization chart and playing "unbound." That means you can just play with whatever you want - no restrictions, no rhyme or reason. There are a few bonuses to playing with a regular force org, but this just smacks of a sales pitch to move more models. I already dislike the allies chart in 6th and it looks like I'm going to dislike 7th even more.
Jervis Johnson talks about it in this video.