Could he do it?
If he was even remotely seriously considering it, he would back out of the fight with maidana and face safe fighters like Manny pacquiao who he can sweep on the cards ala Canelo "hypejob" alvarez.
Not as a WW , the comp is much stronger and much faster at WW and below than it is at LH and above , its an entirely different race , but you would have to understand boxing to understand that , you guys are always trying to put square pegs in to round holes , boxing across the weight divisions is not the same dynamics where you can get away with things at one weightclass that will get you decapitated in another .
If floyd fought nobody bigger than him he could remain unbeaten for a very long time .
If he continues to pick on small brawlers, and fight in his backyard to ensure he will get the nod in a close fight, then yes, he can.
Just stop! Maidana is a lot bigger than Floyd and where do most of the big fights happen again??
No because Floyd still primarily relies on reflexes and when you reach a certain age, even the slightest drop in sharpness can affect you. He is not like Hopkins who is more of a technical fighter.