Most of the time, you just have to learn what makes the new trick the same as the old trick.

Retraining for typesetters meant becoming "prepress" guys, and going from the wide array of tools and hand skills they used to need to Photoshop, Illustrator, and digital imposers and plates. In the process, the job went from a middle-class job to a minimum-wage job, and the bosses who used to respect you (after the union that used to protect you disappeared) became fly-by-night scumbags who treated you like dirt.

As far as I can tell, the entire business for someone who was good at running a press is fancy wedding invitations and business cards with raised type. I am speaking as someone who waltzed into (and later out of) prepress because I knew the digital tools, made no money, and talked with those guys a lot about the past. This discussion would be while we were printing wedding invitations and fancy business cards.

It's simply a different, low-status job now. Retraining is no different than training the first time, because if you want to make a living you either have to somehow be better than the people who started with the new tools (and the new tools don't require as many people) and maybe get into printing packaging or manuals, or you need to do something completely different, and compete with people just starting their careers.

Going to college again is not a trivial thing. The mortgage will still be due.