Floyd isn't going anywhere just yet, win or lose at the age of 30 he has a lot to prove and while there are still big fights to be had with Cotto, Mosley, Margarito or Hatton at 147 then he will fight on for at least another two years. If he beats DLH then he will cop flack for beating a guy 34, inactive and past his best.
If he loses he will say the weight was an issue,the guy is a legend and I bit off more than I could chew.
Mayweather would clean house at Welterweight and unify the title then he would have a genuine claim to being in the top 20 fighters of all time. Losing to DLH will not affect that standing.
He would be foolish to retire. $$$$$ still to be made.