Possibly the remainder of the SW releases. New Ragnar, new Logan, new Ulrik, generic thunderwolf cavalry, maybe a SW vehicle sprue, and/or an Arjac model.
They don't really need new character models (everyone but Ragnar's is cool, Ragnar's imo, is kinda awkward stancewise), except for Arjac perhaps (or a Bjorn model that costs $70).
I would have loved to see thunderwolves, but now i almost hope they hold off since i'm building Dark Elf Cold ones, and Space Marines on Raptors is just awesome (all the same rules minus wolfkin, and they ar totally workable from a fluff perspective).
As for other things, Dreadnaught arms would be much appreciated, especially since 2 of my dreads are from AoBR, which means no fun stuff.
And power armored lightning claws, storm shields, and thunderhammers would be greatly appreciated, though again, long shot.
As for vehicle sprues, unless they make a razorback conversion kit (a real one) then I'm not sure what it would be.