The Hammerhal Herald about the Khainite Shadowstalkers implied that they are actually Chaos. If it's a clue, it might mean that Malerion and the Ulgu aelves are indeed a new Chaos faction, and not Order or part of DoK.
I still think it might be a deamonic faction composed of mostly huge models like SoB (although it contradicts the regular sized models of the new warband)
We might get some answers in 5.5 hours. I'm excited!