I think what happened with the novel was that GW was pushing for a battle-only perspective of the Eternals to give players an idea of their abilities. Kind of par for the course really, the novels made after a release are supposed to show off what the new guys can do. We'll probably see better novels as the mortal realms and their inhabitants are revealed to us.
On to rumors, I was reading this sites current rumors and found Lord Crom to be correct, the quest for Ghal Maraz and the Skaven releases are on the horizon.
(A little caution on the site, my phone had alot of unresponsive problems with it so be careful)http://www.dakkadakka.com/dakkaforum/posts/list/1560/655944.page
Interesting to note, I heard that, besides being the bane of chaos, Ghal Maraz is a large part of Sigmar's powers. One fellow said that Sigmar is actually getting weaker as he reforges the Eternals over and over again. Only the fabled warhammer can give Sigmar his full powers back, so that explains why he hasn't been on the frontlines.
Sigmar's been conserving his powers for maintaining his army, if he gets his hammer back it would be a game changer. We'd probably get to see a Sigmar model finally be made as well.