I think Pac will go a bit out of his game plan as the fight progresses and he starts to get frustrated. He'll take more chances and i don't think the fight will go the distance. He'll either get to Floyd (very unlikely) or Floyd will take him out late (very likely). Just the fact that the two best fighters of this generation are getting it on will mean the fight doesn't have to be THAT great for it to be a classic.
Unless Manny comes in like a bat out of hell when he is behind on the scorecards, I don't see a KO right now. If Manny is overly aggressive then Floyd could stop him.
I've said before in Boxing Forum that Floyd needs to KO Pacquiao to win the fight. He can't let the judges at the ringside make the decision. It's too risk to get robbed.
Both will keep talking out of their asses through the media/twitter/facebook. Make sure *****s and *******s have the upperhand on their ongoing, never-ending debate about who's ducking who. While they both take easy fights to end their careers having never fought each other. Amen.