All depends on how Pacquiao returns. If he's still looking good then it remains a 50/50 fight for me. Mayweather has trouble with fighters that throw a lot of punches nonstop. Add to that Pacquiao's power, speed, stamina, movement and southpaw stance and it's 100% hell for Mayweather even if he wins. Mayweather lacks power so his counters won't exactly drop or stop Pacquiao, he could stun him at very best.
No it wouldn't. Mayweather doesn't exactly commit to his punches as Marquez does. Don't forget the situation Pacquiao was in to leave his self wide open the way he did/was in the fourth fight. You can easily catch Marquez throwing/landing the same exactly punch in all other 3 encounters. The reason why Pacquiao was stopped is because of the third round knockdown. Immediately after that knockdown, he gets back up and you can clearly see him desperately trying to hurt/stop Marquez at any given chance. Once he hurt/dropped him he got far too reckless and bam, it was lights out. Don't expect Mayweather to situate Pacquiao similarly. If Mayweather wins, it would be by out-pointing Pacquiao. As I said, this all depends on how Pacquiao returns, if his punch resistance is gone then a KO for Mayweather is possible. Take away punch resistance from an aggressive fighter and he's done.
Pac will learn not to go in like that in his next few fights. Depends on how he looks in his next fight. If Cotto can bust Mayweather up, then so could Pacquiao.
Anyone who says Mayweather lacks power DKSAB. (Yes you Scar!) every single opponent Mayweather has faced has said completely the opposite yet we have arm chair critics on ESB who have never thrown a punch in their life trying to convince us otherwise. Mayweather is one the fastest punchers and most accurate punchers in boxing today and we all know speed = power and accuracy = power too! Mayweather may not be a big puncher but he has gone up to 154 lbs and never had a problem getting anyone's respect. Now back to the subject at hand he truth is Mayweather hasn't really struggled with anyone besides the first Castillo fight where he was outweighed and according to him injured. Manny has shown that he is a great boxer but been in fights where he was dominating he has struggled to cut off the ring and this was against opponents with inferior foot work to Floyd. PAC also has poor defense, he has great offence and power which covers his poor defense but I feel if he fights Mayweather he will be controlled in terms of distance and pace (can anyone remember an opponent getting Mayweather to fight at their pace?) and he will get hit ALOT. Mayweather is the superior boxer by far and has the physical attributes to make them count and 9 times out of 10 the better boxer wins. Why JMM struggled a little is because he never had the power or speed of manny but look even he gave Manny hell every time they fight. Floyd is taller, faster has longer reach better jab and much better defense, Floyd wins this in a shut out if he decides to take a risk he stops Manny IMHO.
Pac may never be the same. but all things equal.... thatPac would have not been flattened by Floyd. the man was ko'd by another great his kryptonite... Don't you clowns dare make it seem like Floyd could set do that.
I wouldn't consider Marquez his kryptonite persay, if anything they're both each other's kryptonites. They will always give each other 50/50 fights till someone lands the big bomb.
His best bet would be to land early with 3-4 punch combinations, but he's bound to run into some sharp shooting right hand counters like he always does. The difference between Mayweather and so many other fighters Manny has fought and blown out is Mayweather never stays for his big punches, Manny would have to put it together like he did earlier in his career. Its an intriguing fight stylistically, but I can see Mayweather taking over and adjust!ng after a rocky start. I don't see Mayweather knocking him out, however.. like few other people have posted, he just doesn't sit down as much as Marquez, like you said. Its bad Manny got knocked out cold like that, it put out the Manny-Floyd flame, and with Floyd getting older, I really think the fight had more intrigue, Mayweather of a few years ago I'd have favored big time. Still an intriguing fight, but its just not the same anymore.