Detroit Motor Cars

GM, Ford, and Chrysler should merge.

GM has already stated that they want to get rid of or shut down all divisions except Chevy and Cadillac. They have also recently stated that even with $30 billion in bailout money they'll still probably have to file for bankruptcy protection.

Ford has already sold Jaguar, and Land Rover. Next they need to sell their stake in Aston Martin and Mazda. Then shut down Lincoln and Mercury. They also need to sell Volvo, and then they'll be down to just Ford.

Chrysler has already shut down Plymouth, now they need to shut down Dodge and Chrysler branded cars and just stick with JEEP.

If they merged at that point then it would be only Cadillac, Jeep, Ford, and Chevy left all under one company, and they could succeed.
They won't do it correctly though.
They won't be able to pull all of that off however, and they won't merge. most likely what will happen is Ford will end up buying one of the competitors brands, maybe Cadillac or Chrysler and the rest will all go completely out of business within the next 10 years, and there will end up being only one Detroit car company left at the end of it all no matter what they try to do.