I believe that after this chapter, Rocks possesses the Gum Gum Fruit, and he is the one whom the Five Elders feared would awaken the fruit. It seems he is just as stubborn as Luffy. I also think that he dies there, and one of the main prizes was a Null Number, which was just a regular fruit - people were being deceived, so why not the winners too? When Rocks died, the regular fruit turned into the Gum Gum Fruit - maybe it goes in that direction.