i have been wondering the same. Floyd has walked down many fighters except guys like Maidana dn Castillo who went in there to brawl him. I think it will depend on the speed and power Manny shows him in first few rounds. If Floyd doesn't like what he feels, he will not be walking him down. Many have stated that once you feel Manny's speed and power, things change. We shall see.
It's possible that Floyd will try exactly that, use a high guard or half step towards manny. He knows that mixing it up is the key to success, and might want to see how manny reacts, or if he can.