Shields will not get raped he is going to work GSP 10 times harder than he's been worked in his last two fights and GSP may not react well to the pressure. If that happens, he's in big trouble, if it doesn't happen, he will still have to be very careful.
I don't know how you can view this fight as one sided either way, if anything Shields actually has more positives going into the fight. He's bigger, longer win streak, has fought above 170, stylistically poses problems and doesn't carry the pressure of defending the belt.
If GSP was the dangerous striker he's made out to be I'd tip it in his favor, but he's good, NOT dangerous. A clean KO in this fight is very unlikely, so I have to favor the better grappler which is Shields. And don't say this fight won't hit the ground.