No way Bon Kurei is dead. especially since his sacrifice to help save Ace was in vain.
We'll see he's alive and dandy when this arc officially wraps. Dancing in level five, or perhaps when we get the inevitable Hannybal cover story, or escaped by the seat of his pants amidst the chaos of Blackbeard apparently destroying the place.
For crying out loud, the camera even pulled away before we saw Magellan do anything to him. There's a million things (Blackbeard) that could have allowed Bon to survive that encounter. Cripes the next chapter we even had Luffy declare "He's not dead, you don't know that!"
What purpose would Bon's sacrifice and "death" provide in light of Ace dying?
Bon ain't dead, and its silly to assume that he is, given Oda's track record and stances on things.