IF GW bring out a Giant Faction I think they will be usable by all 4 Grand alliances, with different upgrades. The Current Giant fits Ogors O&G and Chaos, so adding Order is easy. Death a bit trickier, maybe a Zombie head, Bone club etc.
But what I think would be really cool, and ties in with hysh more, would be a Teclis faction of Giants.
Morathi made the Khinerai and Melusai with Slaanesh Souls, Teclis messed up the Deepkin with these corrupted souls, what if Teclis decides that the only safe way to resurrect Aelven souls is to place them in Penumbral War Engines.
Clockwork War Constructs powered by the Souls of dead Aelves, might I suggest trapping these Souls in a Gem Stone.