I will agree that anything can happen. But ever since Serra KO'd GSP, he hasn't been in trouble again. He sticks to his gameplan better than anyone and he uses what he knows will win fights. He has become such a force since the Serra fight. And he has proven it with his ridiculous run back to the title and defending it as well.
I don't count Shields out as he is a dangerous fighter on the ground. But I still think that GSP would win this fight big time.
Miesha Tate - Urijah Faber - Dustin Poirier - Frankie Edgar - Diaz Bro's - Claudia Gadelha - Demian Maia - Jessica Eye