There was a time when you had to go to the Mazda dealer for certain things, but now all of the generic shops in our area can handle anything I've run into. Probably no market for a "Mazda" shop, maybe for wankel engine work? You could niche up and become "Mr. Wankel Engine", an expert, source for parts, engine rebuilts, RX restores. May be like specializing in PDP-11s or could be something good???
Mustangs, Mopar, Muscle cars in general are all other places a "little too old" guy could retool for and have age work in their favor. Hell, buy and sell parts for these cars. Buy, restore or wholesale, sell. Buy junk cars for parts and operate a legal chop operation.
Maybe focus on the safety and haz mat aspectics of eletric vehicles. Become "the expert" to help train first responders, a cool and useful consulting job if that is where your heart is. Just some thoughts.