No, I think that’s more of the same flawed thinking. The answer is I don’t know, and further, that trying to predict the outcome of societal change like that i

No, I think that’s more of the same flawed thinking. The answer is I don’t know, and further, that trying to predict the outcome of societal change like that is probably a fool’s game. Pre-emptive, discriminatory rules seem like the absolute worst way to start out. Well, perhaps second worst compared to an outright ban on the technology, which is unfortunately where I think we’ll probably go first due to societal fear of change. Which is ironic given how much you and the OP think it would cause stagnation… You've started by assuming the same as the OP, that having older people will necessarily cause societal stasis. But you're basing that both on a preconception of what you think older people are like now (personally I dispute this, and I'm not that old), and on a supposition that whatever longevity treatment we come up with won't change that. How do we know? How do we know that a particular treatment to, say, keep people younger for longer, wouldn't result in more youthful and dynamic society? We don't know. And any supposition is based on flawed ideas.