I think that if Infinity Ward were to do any sort of mini-game, it wouldn't blatantly copy the zombie theme. I personally think they should leave the zombies to different games. I think the zombies can work well with the Nazis, not because it's ok to dehumanize them, but because they have been so dehumanized over the years. In a modern context, I can't think of any group that wouldn't seem cheesy as zombies. Infinity Ward seems on top of things enough where they can come up with original thoughts for it. If they did have a little "survival" bonus level, it would probably be something like defending a position from the same enemies that you fight in the campaign, like how they used the same enemies in Mile High Club. I would hope it would be like that anyways.
I also hope that they have something like Mile High Club in the new one. I know that plenty of people got pissed off at it, but in recent time, has there been enough challenge in modern games? I find that lots of times the difficulty gets washed down so that Suzy Homemaker or little Billy Anklebiter can beat the game too. Having something that requires absolute precision and execution gives a ridiculous sense of accomplishment after completing it. I know that after I beat MHC on veteran, I hooted and hollered and told all 2 people I pay to be friends what I did. So I applaud the idea of including extremely difficult levels that you (or I) might not be able to beat right away. Wait, I just remembered that they have the Spec. Ops levels included. Hooray! So feel free to apply this soapbox rant to them.