As the age structure 'moves upwards' it shrinks due to some people dying. What I'm guessing is that retirement ages will continue to increase to the point where that birth year group which is the biggest now won't be as large anymore due to attrition - that whatever band where the pyramid is still inverted will simply be defined as "working non-retirement age", even if that is decades older than now.

yes, and back then you could fully retire at a much younger age - in the US at least, the full retirement age keeps increasing, and neither party is going to vote for any policy that allows SS to collapse; just not going to happen.

The fear-mongers have been alive and well for 40+ years, have no doubt they will continue to push the fear - its good for news clips and web clicks, if nothing else.