This is a pretty stacked card, both in terms of talent and how close the fights should be. Only 2 fights scream upset potential but I highly doubt that will happen. Those would be Manny Gamburyan Vs. Rob Emerson and Cheick Kongo Vs. Dan Evensen. If Emerson was to win that would be an upset. I don't know enough about Dan Evensen to say it would be an upset, but after the way the UFC was marketing Kongo it seems like this should be a "gimmie" for him.
If Fitch does beat GSP it will be an upset, but as you said, he does stand a good chance. Hell most of the top of the 170 stands a better than a punchers chance.
But fights like Lesnar/Herring are lopsided. On one hand we have Herring who should have beaten Big Nog if he had just followed up after that punch and is looking good. On the other hand, Lesnar is a freaking beast so we shall see. Florian/Huerta is a very tough fight to call as well. Even though Huerta showed some signs of fatigue vs Clay, I am not sure if it will get that far as Florian has those awesome elbows. But this fight could go the distance.
So with 100% confidence if Rob Emerson wins, then that fight could be considered a true upset as no one is really giving Emerson a chance where as all the other fights it looks like there is a split fence.
Don't censor me bro!