Nonsense. Do you really believe that multimillion dollar plants are just going to sit empty? If GM did cease to exist, something/someone would purchase the plant/equipment and Detroit would be pumping out cars still.
Most likely scenario: GM goes under, everyone loses their job; GM re-opens under new management a week later, everyone's back to work within a month, without unions telling a button pusher they're worth $30/hour; they'll only be paid 15$ an hour, all the employees default on their loans, etc, becuase they're dipcraps and they are living in houses & driving vehicles that factory workers should not be able to afford. Banks in the detrioit area are screwed over; but the rest of the nation's banks will be fine.
GM will now be successful as they don't have the overhead they once did and can afford to sell cars cheaper. Toyota and Honda are now fracked because they can't compete with the low priced american made cars, but the entire country can buy new cars from an american made source.
Banks will eventually rebound, or if they don't new banks will move in, because there's an entire factory of "skilled" labors working & living in mobil homes or apartments, that need to buy that $50,000 house to get back on their feet.
The system will be rebalanced after a couple of years. People will be getting paid what their worth & as long as banks don't give loans to high risk people, banks will rebound.
Capitalism is like a forrest. It will grow for several years and if there are no major fires along they way, dense brush and dead crap will accumulate until there's a huge fracking fire that wipes the slate clean for it to start all over. If this forrest doesn't burn down now, It will just be more fuel for a larger fire down the road.
So eat a dick all you haters.