I believe the American Auto Industry decline began when it somehow became acceptable and "conformance to requirements" to put on 3 bolts where there was supposed to be 4. When the designs were flawed, the materials substandard, the testing a joke and the warranty all but useless. Let's not forget that Asian products were widely considered junk as well.
While the Asians worked hard to improve their products, and did, the American Automobile Manufacturers did not. American cars wouldn't last , fell apart, burned up and blew up.
Most of us felt that going to buy a new car was about the same as having your wisdom teeth extracted; but longer and more painful. At least if you didn't want your wisdom tooth, you went to one dentist, suffered the pain once and it was gone. If you didn't want a car from Dealer A, you had the hellish task of going to Dealer B, C and D.
Everyone shares the blame. Quality, which our fathers, grandfathers and great grandfathers built this country on, was replaced by unmitigated greed. "Quality" became a farce when the requirements were lowered so that junk was "Quality".
Sad to some degree, but from where I sit, entirely predictable.