I guess you disagree with their assertion that the gun industry is immune from lawsuits?
To answer some of your examples:

1. Car into pedestrian. If someone does run over a pedestrian, they can sue everyone they want. If a gun is used the manufacturer cannot be sued. The car company would have no liability, unless it is found they marketed a new line of cars specifically to people who like to run over pedestrians...and added special features.
2. Baseball bat and Walmart is a false comparison. To compare it to gun manufacturers, you'd have to sue the baseball bat manufacturer. They might be liable, if they had a special line of bats designed specially for murderous people...with special hand grips and shit. In this example, Walmart and the baseball bat manufacturer would win any lawsuit...but they could be sued. Not a gun manufacturer. And, since you brought up Walmart, and they are the largest ammo dealer in America, they COULD be sued for gun deaths. They'd win the suit, unless they knowingly sold ammo to a killer.
   Product liability is a complex field and allows for almost anyone to sue anyone else.
   Gun manufacturers and a few other industries are exempt from such civil lawsuits.
   Gun manufactures would only go bankrupt, if they had marketing practices that did nothing to ensure their weapons and ammo don't get in the wrong hands.
   I don't think the gun manufacturers are quite the incompetent business people you claim they are. I think they would adapt, if they played by the same rules everyone else does...they'd figure it out.
   The right to bear arms doesn't include the right to manufacturer and distribute weapons of war to civilians. I re-read my pocket Constitution twice, honest.