User blog comment:Badmandan/Zombies in MW3?/@comment-1816803-20110729201228/@comment-4731619-20110729204556

It says in the blog that IW said they're not gonna do Zombies. I think Infinity Ward wouldn't be able to 'do' Zombies as good as Treyarch. As Treyarch has planned everything out, and knows how to do all the power-ups, perks and pack-a-punch in perfect balance. By balance I'll give an example, you'll most likely die when Fire Sale is on because you get distracted by the need to use the box.

Shangri-La is also good for power-up balance because you must sacrifice Max Ammo to get Random Perk Bottle. I don't think IW would know how to do that properly, unless they had guidance by Treyarch