Hell no. Duran beat Leonard for crying out loud. Pacquiao won't even beat Mayweather. Duran was the more skilled fighter, Duran would beat Pacquiao head to head, and Duran has the better wins on his resume. If Pac beats Mayweather, it could happen. However, he's going to lose to Floyd.
Manny would have to fight a little longer than he plans to surpass Duran. Personally, I think he's almost there. 7 time champ in 7 divisions. 4 lineals. Titles in This content is protected of the original 8 weight divisions (Henry Armstrong had titles in 3 of the original 8. It seems his success at the lower weights isn't being credited for enough.
How do you see the fight going McGrain? Do you see Pacquiao having a big chance? Or will Floyd just be too elusive and just too defensively good for him and will most likely potshot his way to a wide UD? Does Mayweather have the power to keep Pacquiao off him for 12 rounds?