I think if Halo 3 launched at the Wii/PS3 launch like MS wanted, they would have stolen a little Wii thunder, and made the PS3 launch look even worse than it was.
-What if MS had built-in HD-DVD player for use with movies and games?
-What if MS lowers all 360 SKUs by $50?
-What if Sony had bitten the bullet at launch and somehow launched PS3 at a competitive price?