I’ve got flash news then: unless I want 70 years old people to work production lines, my job (a developer) can be done by a seventy years old person. Or a job of an artist. Or <insert bunch of professions here>. Physical strength does naturally deteriorate, and that is the only thing that actually is does.

Now, to the more important: producing goods? Really? Since when has it become the only thing you look at? And since when producing goods is something only people-under-random-age-limit can do?