Not many people work on their cars anymore. It’s not even hard to find an upper-middle-class and higher town which has no auto parts stores at all, because people just drive it to the dealership for everything so the parts store has no one to sell anything to.
A few of us in my neighborhood are gearheads. One even has a lift in his garage that he’s using on his muscle car restoration project.
But we all get quizzical looks from the other neighbors. They don’t understand why we spend a perfectly good Saturday with our legs sticking out from under a car rather than just taking it in and having the work done for us.
In short, I don’t think a DIY-serviceable car would find much of a market even if you could get around emissions/efficiency requirements so that you wouldn’t have to have everything computerized.
Now, maybe that will change in the future as electric cars become more common. Mechanics might find themselves being thinned out because they’ll have less to do, and maybe that will spur people to do their own work at home rather than having to drive 50 miles to the nearest surviving shop.
But I doubt it - especially since some of the electrics out now have concierge services where they come out and take your car to the shop for you, leaving you a loaner in its place.