I work in heavy industry - big trucks, cranes, noisy machinery, welding, mining, structures, ship-fitting, etc - and one thing that's very apparent, if not worrisome, is how hands-on mechanical aptitude will be thoroughly erroded once the 50s/60s are no longer on the job.
Take the construction and maintenance of a long-haul, pressured piping system for instance. Operations of all mechanical equipment is primarily operated by automation: charging pumps, valves, strainers, purifiers, heaters/chillers. The 20s/30s can naturally interpret the entire system through automation screens. If a pump goes offline it's not hard for them to make up for it by finding other pumps to bring online and orient flow by automation screens.
What worries me is when specific equipment requires onsite, hands-on repair. You're hard pressed to find anybody under 40 with natural instincts for taking apart, diagnosing for repair, and reassembling pumps, valves, etc. When it comes to my work I'm very thankful for my coworkers in their 50s/60s (many are Navy vets) who can be left to the greasier, hands-on side of the job.
Goes to show you how a generation (Millenial & Z) of playing video games and bitching about Star Wars (while out in the garage Dad and Grandpa (X & Boomer) fixed the lawnmower motor themselves) is quite the foreshadowing to what can be expected of differing technical aptitudes going forward.
So, I wonder if there's something more beyond the video game/lawnmower dynamic. Maybe we have fewer tinkerers, but I wonder if we're shifting them around differently. A few random guesses.
-More tinkerers are being directed toward engineering schools, which leads to a white collar-ization of the talent pool
-Many things became more complicated, so fixing say a car without messing something else up because a trickier (my dad could rebuild an engine as a teen. He cannon build the onboard computer system in my old 2003 Toyota). Thus, you have a higher barrier of entry early on.
-Mechanical goods grew cheaper, so a lawnmower is less often fixed because you NEED to do it, so only a really dedicated tinkerer makes the effort
-The emphasis on college in the education system and general disinterest in funding the endeavor led to a stigmatization of vocational education, which helps train those instincts and direct kids to interest in them
-You mentioned Navy vets, and I think as the military has become more automated and college became more a bridge from 18 to 22, you narrow a key path to those skills. The military has tons of machines. They have lots of people they need to find something to do with (a person I met basically said her time in the army taught her that the military is just gonna keep trying to put you to some use). More people used to go into service (esp from less privileged backgrounds). That meant more people in position to be shoved into those roles.
-I also wonder about market forces. Are there more of those repair roles, or less. If it's less, is the older generation holding onto roles for longer? I used to work at a business with a big piece of machinery that was going off line. A huge part of the operators' job was diagnosing and swapping out pieces on the fly. But we phased that machinery out, and those guys are in a real tight spot job-wise.
It's an interesting spot. I have family that was kinda in that cadre and just retired.