New research reveals longevity gains slowing, life expectancy of 100 unlikely

Right, we’ll just replace ourselves with humanoid robots. Only half joking

You know this is how we will end eventually in the best case. We won’t master our biology, we will simply transcend it by pro-creating offspring that have something better. It’s also a much easier solution than untangling evolved biological systems that are not designed to last for what have been very beneficial reasons (e.g. scientific advances occur via death of the old guard).

Not even that. I guarantee you that once really good brain computer interfaces are a thing, investments into "brain in a vat" companies are going to start being a thing. Because keeping just the brain young and then alive is almost certainly very possible if that's the whole focus.

I think this is reasonably likely.

We need to remember that our bodies are evolutionarily optimized for getting to childbearing years, and then living long enough to get our children to a point where they can be independent. After that there are really no evolutionary pressures keeping us around.

Untangling all that and re-engineering ourselves (biologically) to overcome that is probably a pretty monumental task; starting from scratch with something simpler (and perhaps non-biological) might be easier, with sufficiently advanced technology.

Arguably there are some evolutionary advantages to the presence of elders in social species with cultural transmission but your point stands