I would really like to see IG, but Tau tends to pull juuuust ahead of them in the polls so if it's based on popularity contest it'll probably be Tau, then IG for 6th. Though there's also the possibility that both could come out in the same expansion, if the devs want to keep the number of factions even. And since they both fall into the category of "squishy shooty armies with pretty good vehicles", it would make sense for them to be together in a themed expansion.
Well, with the inevitable victory of the Chaos Gods and their Chosen Lords, Arkhona was destroyed, the habitabal planets of it's system left in ruins by a combination of warp taint and the impregnation of their once resource-rich soil by both Greenskin spores and Tyranid seeding. The 4 races shook hands and agreed to meet again next Spring Break (expansion) in the Eastern Fringes, but not before all of them had real coming-of-age lessons that ushered them into manhood. The End. Also the Necrons are Transformers now. ~Matt Ward
Necrons. NO. All 'Crons above Warriors are fully sentient individuals. There is NO reason for them to be npcs.