From a PPV POV, Floyd would still be a bigger event. (Even though everybody claims they wouldn't buy it).
Better for him to go out with a loss to the best fighter of his gemeration, instead of getting sparked by one of these young guns.
But who, I can't think of any immediate threat that he probably wouldn't beat. Beyond maybe Thurman or Crawford. Sadam Ali will be his greatest threat, but he's still years apart. I think indeed it will become a fight of leftovers, cause I would say Pac vs Maidana in Manilla would be excellent. Heck maybe even Fight of the Year potential.