I was thinking of steam locomotive enthusiasts, actually. I mean, yes, if the future of coding is similar, it would be a pretty sad, farty old hobbyist world to be consigned to. But some people understand steam engines very well, and this isn't for anything except steam engines. You get a bunch of subtle side-benefits: generic problem-solving is transferable, which in this case isn't completely generic either because the general domain is engineering and physics. There's also the history angle. It's also just interesting: who knows what the benefit is? Many assorted inspirations may crop up from the stimulation, like with pure mathematics.

But it doesn't have to be so brutally outcome-based as you're demanding, although you do get a ride on a steam train out of it too.

It's not entirely unprofitable, either, if that matters. Niche.