I'll bet he would sell the "0" for the right amount of money. It would take a lot but I think he would do it.
I'd say Pac rematch. I'm honestly not all that interested to see him come back though, he's had a good career, nothing more to prove. I'd rather him just stay retired then come back and potentially lose because he's too old.
I thought Mayweather looked terrible against McGregor. If Floyd came back, I think the top welters would beat him rather easily. He'd look like Ray Leonard against Terry Norris.
There would actually be quite a few good matchups waiting for him if he returned now. In order of those I’d most like to see: 1) Canelo at 160 2) Crawford at 147 3) Golovkin at 160 4) Spence at 147 5) Pacquiao at 147 6) Loma at 135-140 (assuming Floyd could still make this weight) 7) Jermell Charlo at 154