Looking at it, I think I know their plan now. Orks are being updated with a reprint of their 7E supplement, including new formations. I'm guessing they'll give them a decurion at the same time. The only other books besides SW and Orks that are 7E but released before Necrons (first decurions) are Grey Knights, Dark Eldar, and Blood Angels. Now I'm gonna say we will see all of them before anything else from 6E gets updated. I'm a pessimist, what can I say.