Now, I know this won't happen but this is just an observation. Smoker, Akainu and Crocodile have two things in common. They smoke and use Logia fruits. Sanji smokes. Could that be a hint to something. Of course, he is the swimmer of the crew so I guess if he gets a fruit it would defeat that purpose but as I said, just an observation.
It would be funny if he goes from cigarettes to cigars once he starts using his fruit to show his progression of badassness.