I'm curious about the state of research on longevity for model organisms. Especially C-Elegans, or something else comparatively "simple" to a human. If we can't manipulate lifespan significantly in those, I don't see much hope for it in humans. Phrased a different way: I think extending flatworm lifespan is a prerequisite for extending human lifespan, at least in a systematic way.

I'm not optimistic we'll have real breakthroughs in this field within the next century or so, but the gut reactions to the field (See the acerbic tone of the linked article) are born more out of a knee-jerk reaction to what longevity research implies, than a rational take. When the arguments go towards societal sustainability or "I wouldn't want to live any longer than 90", it's a cue you're reading a skin-deep reaction.