I dont think there is possibility of a nuclear exchange as long as Punjabi Muslims are the dominant group in Pakistan. These guys, while full of bluff and bluster and false machismo, are not hotheads. They love life too much to invite death for any cause. While Kashmir is a desirable trophy, its not worth dying for. The problem will come only if the Taliban / Pukhtoon types get their hands on the bombs. They are the non-thinking martyr types.
You are right on this. Pashtuns are a daredevil crazy bunch ,violent to the hilt.