Personally, I think the optimal aim is agelessness. There are issues with immortality, as there is with any unlimited concept.
I think what most people fear is a fixed time limit. I want to be the master of my own destiny, and not have biology telling me when to go. if we become ageless, people still die from trauma and suicide, but we lose that pressure of knowing we have such a limited time. That might be good for altruism, long term outlooks, and delayed rewards. Plus it addresses another major issue: the slow decline into frailty.
I think by becoming ageless we can gain many advantages of immortality and avoid many of the problems.
All these issues can also be overcome with a "live and let live" attitude, and expanding ones empathy beyond oneself, and tentatively even beyond the present. At least to me, the main difference between me living for 1000 years, and me and 9 other people living 100 years each, is that 10 people would probably be more interesting, even though I would only get to see a tenth of it.
Like that Roman dude said, the mind is a fire to be kindled, not a vessel to be filled, so it seems with life. To have or to be... if only I could live 1000 years, if only 10000, if only 100000... is it so absurd to at least consider it possible that we would treat it just like we treat RAM and CPU now?
Sure, it's apples and oranges in a way, but satisfaction really is something that happens in the mind and not just the external circumstances, so I don't see why we wouldn't be able to consider any amount of time "not long enough" at some point. Doesn't mean we would, but if we did, we would have gained nothing, other than less diversity of persons.
> We feel free to express ourselves because we are ready to fade into emptiness. When we are trying to be active and special and to accomplish something, we cannot express ourselves... So we have enjoyment, we are free.
-- Shunryu Suzuki
> Of short duration are those who praise as well as those who are praised, those who remember and those who are remembered. And even that happens just in one corner of the world, and even there not everybody agrees with one another, a single person doesn't even agree with themselves. This whole Earth however is but a dot.
-- Marcus Aurelius
This does not change meaningfully, to me, if you replace Earth with Universe and short duration with 10^10000 years. It's the same basic problem, and even I am constantly in flux, not ever the exact same person I was an instant ago. So why not get over that? For me letting go of some things doesn't mean giving anything up, it's more like having the hands free to receive better things; I like the tiny actual place I have in reality more than an imaginary big one that requires all sorts of ballast and images, layers of abstraction and alienation.
I think by becoming ageless we can gain many advantages of immortality and avoid many of the problems.