Retirement age used to be the point where people were physically unable to work, with justifications being that past 65 workers were completely unable to do anything useful [0]. If jobs have changed enough that a 70 year old can be productive (and they can) this represents a reversion to an anachronistic mean rather than death throes.
If you want death throws of capitalism, look to whatever [1, 2] changed in the 1970s that delinked wage growth and productivity; the pressure that forced the US to abandon the gold standard is probably also the pressure responsible for a lot of other ills that are building with time. It isn't a fast process.
[0] https://en.wikipedia.org/wiki/History_of_retirement