There's a seventh, which is that we gain complete control over the decline stage and are able to reverse it. That's the one I actually envision. (Hard to imagin

There's a seventh, which is that we gain complete control over the decline stage and are able to reverse it. That's the one I actually envision. (Hard to imagine it not happening in the long run, barring serious technological stagnation.) However, it might be quite a few lifetimes before we hit that technological point, and people would be making do with inferior tech in the mean time. One possibility is that before we get there, we might go through a phase of relatively crappy extension where we tend to end up stuck at a plateau somewhere towards the end of the decline stage. What I'm basing this on is the fact that (according to Michael Rose) fruit flies and other organisms reach a senescence plateau where their rate of death stops increasing with time, instead remaining at some fixed percentage rate per hour death rate stays constant. In biological terms that means they aren't aging any more, i.e. the death rate is not going up. He claims this happens in people too, just at a very late stage in the life cycle. The idea I am going for is that idealized life support systems, robotic exosuits, implantable organs, and so forth could act as a crude counterbalance for the death probability (taking it to near zero) without actually altering the fact that your body has aged (i.e. would die very soon on average without the external life support).