It would be practically impossible in another 5 fights to get to the level of greatness that the legends of the sport have commanded. Many fought so many more times than Floyd, and against many other legendary fighters.
That said Floyd's record and ability does command notice......I can't think of many welterweights in history that I would pick to beat Floyd. His resume isn't bad at all! He is a sure fire ATG and one of the most talented to have ever laced them up.
To be in with a serious shout at being the GOAT; after Cotto, he'd have to absolutely annihilate Pacquiou. There would be nothing much left at welterweight for him at that point. khan might be a good fight?!
If he were then to do some division dancing and were to defeat say Sergio Martinez at middleweight, then Andre Ward at super middleweight.....believe me, people would be seriously impressed. Then to crown it all, beat the winner of Hopkins vs Dawson at light heavyweight!! Then and just then might people start to think that he might be better than Robinson and the rest!
This is all far too far fetched though. You might as well say that after Cotto he should bulk up with a view to toppling one of the Klitschkos!