[anyfoo]

I know exactly what you mean, people being proficient in some very specific legacy domain (Vax BASIC is a good example, another might be AS/400/IBM i by now). Often going above and beyond in their niche expertise.

Though it's hard to get a full picture. Maybe past gigs or other circumstances have given them enough financial stability that they don't strictly need to work anymore. They then continue consulting out of passion for their particular niche, or somewhat opposite because they don't have any drive to learn anything else, but still don't want to retire completely. I feel like the people I have in mind there seem to be in a more good than bad situation.

But I've also encountered the other category you're hinting at, people who are fused to a legacy system (i.e. a particular project at a particular company), not a technology in general. A few friends of mine do that, and they are much younger and much further away from feasible retirement than the aforementioned "gray beards". I sometimes do wonder about their prospects, but, again, no full insight.

[wpietri]

Definitely. If somebody is winding down their career, I totally get just sticking with the thing they know. A couple years back I decided I wanted to try my hand at building a mobile app. Starting from square one kinda sucked; suddenly being bad at something I am used to being good at was a drain. The ROI on a switch like that depends a lot on how many years you expect you can be putting the knowledge to use.

And yeah, I too worry about people who do that early on. Some things will probably last. E.g., I'd bet that Salesforce admins will still be employed 30 years from now. But the odds are not as good for most technologies in use today.