Something catastrophic would happen. Their in-ear monitors would break and they would sound terrible, then Chester will get a wardrobe malfunction. And a shadow on their guitars would look phallic and the news would never stop talking about it.
If Jay-Z were to do the Super Bowl, I could see LP coming out for Numb/Encore and another song from Collision Course but that's about it as far as what's probably realistic.
I think they'd be amazing, the problem I see is the lyrics, They're very personal and often painful, or very political. The Producers aren't gonna go for that
After watching some performances I think they could play a setlist of What Ive Done, The Catalyst, In The End, and finish with Faint with extended outro(rock am ring 2007 style) and that would be a good superbowl performance to me. Maybe J could come play Numb/Encore