The WWE has given themselves and "out" in a situation like this. They did it very recently with Ryback v Punk which turned into Ryback & Team Hell No v The Shield. Apparently the 30 day title defense rule has been swept under the rug. They could easily make this a #1 contenders match, but then again, what would they be going up the ladder for? A briefcase, a clipboard with a contract? Seems a little lame... especially since the briefcase signifies the MITB. Personally, I think Ziggler is a little overrated. I appreciate his speaking ability, athleticism and acceptance of moves, but aside of that... meh.
So I do like the idea of having a battle royal to determine the 3rd guy and stripping Ziggler of the title for medical reasons. However, when the WWE does stuff like this, the new guy is usually the one who wins. Christian might be great in this spot as he's really the only guy at this level who doesnt have a program right now.