Once upon a time, Nicolas Cage almost played Superman. In a movie directed by Tim Burton. From a script by Kevin Smith. Which was based on the iconic "Death of Superman" comic book storyline. And then it all fell apart, transforming it into one of Hollywood's greatest "What if?" narratives. 'Superman Lives' may have died before making it in front of cameras, but at least the new documentary 'The Death of Superman Lives' will give us an insider's look at what went wrong.