Not to contradict your point, but what matters from this perspective is healthy life, not lifespan. If you're healthy enough that working to maintain whatever

Not to contradict your point, but what matters from this perspective is healthy life, not lifespan. If you're healthy enough that working to maintain whatever income you need or want (you might work less, because you need less, or go without working if you can; this is about having the option) remains a reasonable prospect till 75, and drop dead at 76, then retirement isn't a huge issue. We don't, strictly speaking, need people to live to be 150 to solve the retirement problem. (In fact, them living that long in poor health would be counterproductive; however, it's almost a certainty that radical life extension requires rejuvenation.) We just need for people to be healthy and able to work while they are alive.