As an over-40 developer, I haven't really experienced that latter. However, I have experienced the feeling that I've passed my due-date, culturally, in more-or-less the way the article describes. People look to me to provide answers, now, even when I don't know them off the top of my head, and accept my answers as correct even when I preface them with conditionals and hedging. I know exactly the feeling that I am now responsible for creating culture for those under 30.
People have been looking to me to provide professional answers almost since I started my career - I've historically been the best, or one of the best, developers everywhere I worked.
Younger people I've known are typically headstrong in the ignorant way of youth - they can't help it, they don't know what they don't know. I haven't seen young people pay particular attention to what older people say.
But young people aren't usually very interesting, so not being culturally relevant to them doesn't really affect me in any way.
