You're engaging in one-bit reasoning where longevity treatments are either a magic fountain of youth, stopping aging and disease completely, or they don't work at all. But how can we know how well they will work?
I think it's more likely that the first ones could add years or decades of life without being nearly that good, and perhaps still having significant side effects or just not affecting some aspects of aging. If so, difficult decisions about what to do when closer to death won't go away.
Those difficult decisions are there right now; life extensions just push them further away. I don't see the problem here. And yes, longevity treatments will necessarily involve reducing disease and aging, or else they won't increase your lifespan. Aging is simply a disease, where much like AIDS causes your immune system to fail which causes other diseases to kill you, with aging some other aging-related disease finally kills you, such as Alzheimer's, cancer, heart disease, etc. Longevity treatments will necessarily result in less disease, even if they can't figure out how to stop all diseases right away. I don't see how they'll result in hordes of centenarians on life support.
I'm not saying there is any new problem, just that the problems of aging may still be rather similar to today, just happening later.
If life doesn't really go on forever and people still eventually die of some disease or other, that's a lot of old people who are on life support at some point in their lives, right? Just like today.
As AstralStorm said, you just made the argument for why it should be pursued. If you look at humans as economic units, we as a society invest an incredible amount of time and resources into every person to make them a productive adult: it takes a bare minimum of 18 years, and generally more like 22-26, with a lot of education and other resources. Then if they're too feeble to be productive by the time they're 70, that's only 40-something years. If you extend the lifespan just so they can be productive until 110, you've now doubled your return on that investment!
On top of that, now with people delaying parenthood so much, or not even having kids, we're facing demographic problems (too many old people being supported by too few young workers). If people have significantly longer adult lives, this could very well make it more feasible and desirable to have kids at older ages, which could stabilize the population problem. (People could have two kids at 40, and two more at 60, and two more at 80, for instance.)
I'm not sure I buy your arguments, though. For people who earn enough to retire and live off investments, this could mean more time in retirement, rather than more time working. (Still good, but not a productivity boost.)
Also, I don't see a reason to assume that an anti-aging treatment would delay the end of fertility in women past 35 or so, or make egg freezing work for longer. Those would be separate medical advances.
>For people who earn enough to retire and live off investments, this could mean more time in retirement, rather than more time working. (Still good, but not a productivity boost.)
Who cares? As long as they're not a drain on the system (compared to today), what's the problem? That sounds like a big plus actually: people getting to enjoy more time in their lives. Why would anyone not want that, unless they're some kind of religious nut who thinks this isn't "god's will" or something?
>Also, I don't see a reason to assume that an anti-aging treatment would delay the end of fertility in women past 35 or so, or make egg freezing work for longer. Those would be separate medical advances.
I don't think they'd be entirely separate. We can already freeze eggs, and women are able to carry children at older ages (sometimes not even their own children) thanks to IVF now. Anti-aging treatments should make this even better; women may routinely get their eggs frozen at 25, and then use them to make children at 75.
I think it's more likely that the first ones could add years or decades of life without being nearly that good, and perhaps still having significant side effects or just not affecting some aspects of aging. If so, difficult decisions about what to do when closer to death won't go away.