Replacing organs isn't good enough. We need to create genetic immortality fortified by nano bots, and the ability to preserve and digitize brains. The rich and those proven useful are going to form a technocracy sooner or later, probably long before it's feasible for off world populations. No one wants to admit it, but ballooning population could easily undo us all.
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I wouldn't mind extending my life indefinitely, but then I'm not one of those yolo types either.