I like your enthusiasm!
With Darnok's rumors of the Necron codex release at the end of January and how it was with Orks-
SW and Tyranids-Blood Angels we COULD see a new campaign featuring Necrons and at least one more faction after the necron codex - in February 2015. But this is the rumor section and not a place to predict things that could happen
By the way Devourer is an already released Black Library novel