Chaos Eldar have even got their own Phoenix Lord
Arhra - The Fallen Phoenix who burns with the dark light of chaos.
I don't think he's Drazhar as Dark Eldar don't tolerate chaos as it could break Commoragh by causing dysjunctions.
I'd love Drazhar to turn out to be someone else, like Drastanta from the shining spears just to mix things up :D
But I'd absolutely love a full Chaos Eldar Faction.