Exactly why Harry couldn’t die. Rowling couldn’t have the message of her story be “none of that fighting matters, good can’t really win” could she?
Fairy tales need the hero to marry the princess at the end. That’s how they work.
Especially if he dies when he appears to die. She could sort of get away with the final battle resulting in both Voldy and Harry dieing, but to die while Voldy still lives (even if he is killed later by somebody else) would seriously damage the moral of the story.
Spot on. The moral couldn't be: stand up for what's right and die anyway.
Just as the dark wizard Grindelwald was defeated, and Voldemort was defeated, 20 years from now there will be another dark wizard to defeat.