Really not a big deal. Think about it. The writers could simply make Batman an idea instead of a person. Batman beyond is a prime example of that. Batman never really dies because he's more than a person. He's an idea. Or if they want to make Batman Not just an idea but a person. You can just simply work back in the conversation of the Lazarus pits. Or maybe Batman switches tactics and goes tomb raider and on some sort of adventure. In which case he finds a magic jam or Jewel or some rock of power that restores his youth and gives him renewed strength. It's a comic book based on fantasy, not reality. We can really take this anywhere. But I do like the idea of a rider exploring Batman getting old simply because I can relate to that. That doesn't mean that. That's the one story that defines Batman forever