It's no coincidence that many old farts made their best work when they were comparatively young.
God forbid that the young should ever stop challenging the old.
I'm not really convinced of that; Lindbergh is cracking on with great stuff and Feurer too; Avedon didn't exactly go off and Newton would still be doing it had his ticker not done for him as he drove his car out of that hotel... I think that what does change with some of these older stars is that their interests - if not opportunities - go elsewhere. I can quite understand how that can happen after a while.
The young are constantly challenging the previous generations, and for as long as the challengers produce great stuff, long may it continue. Bailey challenged French and won, but both were/are very good at making photographs. That is a different conversation.
Actually, thinking of the relative youth of the photo-art business, Penn was no slouch, and would send assistants down into the streets to pick up cigarette butts and bits of litter; I believe that one was scolded for trying to make it look more tidy and clean. Quite interesting on 8x10...
:-)