[unnouinceput]

Exactly this. As becoming older you also get experience, experience very few have. I was at one meeting with several people from a company that hired me as external contractor and several people from their client company. And an issue arrived at the table, a technical issue none of their staffers or client's staffer could explain/solve (both technical and non-technical people were at that meeting). So they asked me to weight in my input. After a round of questions from my side I told the most technical people there I thought he could understand, to do XYZ. He did it and just like that the problem went away. XYZ was a very weird combination that none fully understood how that could be the solution. When they asked me how did I know that I said only one word "experience". That's what you pick up over the years, the truest form of knowledge, the one that makes you to be more expensive. Because just like that particular problem where they wasted at least 100 hours of different people trying to solve it and in itself the problem also made their process more expensive, having a person that can solve this type of problems is the make or break of a company.

[ghaff]

The flip side is that, if expertise in XYZ is no longer valued, that can be an issue. I've known people who were essentially the world experts in some narrow area of technology or business and that became irrelevant which was a tough situation to be in.

It's easy to say that people should keep skills up-to-date but if you're truly a world-class expert in X, it's hard to transfer that level of skill to Y. That's a different level from junior competency in one language picking up another language.

I know someone at a largely military sub talking about bringing in "geezers" to consult on some very specific classes of problems.

[unnouinceput]

You misunderstood me. In my example XYZ was a combination of specific Windows API's to be called, not a technology. For the foreseeable future Windows is here to stay, and regardless of the programming language used if you learn its API's you'll be king.