5 round? I doubt that Manny can do that, Floyd was extended to 10 rounds by Conor. I think one reason is that Floyd wanted to entertain the crowd. But I don't think that Manny is interested on that money fight though, Floyd or any top welterweight next year will be the goal.
If i borrow the words of Manny's trainer Freddie Roach there was a time when Manny was focusing on religious grounds and he was not interested to hurt anyone but wanted to win the fight by points and if he is on that mind set then you might need more than 5 rounds, if not Connor will not last that many rounds against aggressive boxing of Manny Pacquiao. With all the media outlets wanting to see a rematch between Mayweather i am sure it is possible to see around next year.