Say the lifespan doesn't become infinity, but rather 10x ~ 800years. How do you imagine things to change? It would certainly mean that people can take up much more ambitious projects instead of the usual ~30 year constraint.
I do share your view that positive direction is not a given, but what evidence do we have that it would be worse than right now. Maybe we should be cautious of the risks.
I am simply saying that we don't have evidence either way, though if development of medical knowledge is any proof, we mostly keep learning how much we don't know (if you've ever faced any uncommon and thus unusual medical predicament, you'd know what I mean).
Heck, so much money has gone into preventing hair loss, and there does not seem to be a simple answer to that either ;)