It all depends, as people have already stated.
In this show where Naruto has never once shut up about becoming a Hokage, and how we keep getting speeches about his inevitable greatness rubbed in our faces, it's hard to believe he won't survive. The entire story would be more or less wasted.
I think killing a character, especially THE main character, is harder to pull off right than most here realize. You have to make sure it counts, that it feels relevant to the story, that the sacrifice is worth it and that everybody actually cares about the character. Just adding it for the sake of trying to pull a plot twist or making your work seem deeper than it actually is is idiotic.