About those 40K suggestions - there will surely be rules changes for it especially about ranged attacks: at least 4 out of 6 sides of the dice should hit, range should factor into the effectiveness of ranged attacks (kind of like it does in X-Wing), etc.
Apart form that I'm pretty sure we'll see some combination of customising heroes, collecting artifacts (as someone suggested), some story driven campaign probably, neutrals/mobs, as well as all the iconic Warhammer unit types that are still missing (squigs, goblins and snotlings, witch hunters, more mages, beastmen, etc. etc.)
I just hope those won't be too similar to each other (as a lot of disks in the core set are). Not too worried though - after all they're mostly relying on core mechanics now so more complexity can be introduced later.
A lot of ground to cover!!