Neuromancer said:If we're in the world of the comics let's face it people, this is an unwinnable game.
Also true.
Superheroes and their villains can only really die or be permanently retired in limited, self-contained adaptations.
In almost any given main continuity, superhero comics are a soap opera in which there is literally no shortage of ways to live forever or resurrect. Temporary setbacks at most are all that will happen, unless a character is unpopular. Joker is exceedingly popular.