> At some point, you could take 100% of the output of the productive people and it would still not be enough to support retirees et al.

But productivity for productive people is increasing. Is there an assumption that retiree spending is also going to increase to match?

Realistic solutions look something like: - we increase productivity of the working population - we lock or decrease the per-year, per-person spending on retirees - we decrease the % of their lives that people spend retired