Well i guess so many people were desperate for the nids that they had to cut chaos in the end. As for which faction they will choose it could go any way.
It would be great to see chaos get 4 commanders to choose from at the start. One for each of there gods. As brill as that would be i think we will get a near identical DOW1 chaos with some new bits thrown in.
One thing they could always do is bring back the super units for each side. Orks could get their giant squig back etc although it would prob mess up the tactical gameplay relic have gone for.
I would like some proper drop pods for the space marines. maybe send your units into the HQ then have a ability to drop pod then into battle, similar to DOW1 teleport but only with the proper pods