I'm 30 now and having the first minor issues of my body not working as great as before, I can't imagine how it is at 70. The simple fact is that almost no full-time career job (except for politician apparently) can be fully filled by the average 70 year old.
Either the vast majority of our productivity gains will to to pensions in the future (as they already do in Europe), or retired people will have to live with severe cuts to living standards.
It seems to me that pretty much any job not involving physical labor could be filled by a 70-year old. Why would someone 60+ not be able to be a banker, a civil servant or even a lathe worker? There's a vast amount of jobs these days that don't involve much or any physical labor at all.
I think the real challenge, at least in the western world, will be getting people to work when retirement at a "normal" age is not on the table. A lot of people work boring jobs with the knowledge that they're done at 60 or 65 and if health permits can have 10-20 years of nice retirement. It's going to be a tough sell for a lot of jobs to convince people to want to just do them until they die. For interesting jobs, I think many do this anyway, but if you're some pointless cog in a bureaucracy, you're probably just counting down days to get your pension. Losing that would make people rethink the whole thing (and hopefully enjoy themselves more)
This attitude of many people makes me sad. Working and thus wasting your whole life in a miserable job and just waiting for retirement. Feels like a recipe for disaster.
Either the vast majority of our productivity gains will to to pensions in the future (as they already do in Europe), or retired people will have to live with severe cuts to living standards.