Assuming there will be Elf Sets, of course.
Personally, I'm looking forward to graceful, simple designs. Not a lot of ornamentation, but maybe some clever SNOT. The architecture should look organic and wooden. Lots of brown and green. I also want lots of bows in the new brown, and katanas as well. In fact, the orcs got a new mold for their swords; why not the elves?
Plenty of minifigures are also a must. I'm thinking Dark Forest-esque torsos and brown or green capes. I'd also like a lot of horses, maybe in a new color like tan or burnt orange. In fact, I'd like an Impulse set with a horse, a longbow, a cape, and a katana. Because mounted archers are awesome.
One other point: don't kill me, but I think that Elves should be fleshies. It would really set them apart without resorting to helmets with pointy ears or something. It would also give all the other peach heads a use, or at least an explanation.
And no beards. Elves do not have beards.