It was and has always been unpredictable. This one just adds more doubt and makes Pakistan's work harder. Good thing is time to react is small so most likely they will know that missile has hit and this is the damage before going for a reaction. Bad thing is time to react is low so they may react massively even on a false alarm.The point is that it is unpredictable; it has become unpredictable. Now they have to decide if there is a nuclear warhead on that missile or not. They have to decide and react.
Hopefully a hotline always exists and remains manned to avoid any misunderstanding. I think there is one.