User blog comment:Togageru/death/@comment-4493594-20111010103848

Random extras with speaking parts are the first to die.

Okay, seriously... none of the SHs will ever die. They are immortal. The villains on Fishman Island MIGHT die to mark a turning point of the story and break the tradition of villain's surviving in the past in order to show "This is the New World. This is not a game."

Other than that, I can't think of any meaningful death of any existing character at this moment.

EDIT: The more I think about it the likelier it seems to me that Luffy might die at the end of the story.