The hazard lights go on, the car will slow down, and eventually pull over to the side of the road while Autopilot is disabled for the rest of the trip. Though t

The hazard lights go on, the car will slow down, and eventually pull over to the side of the road while Autopilot is disabled for the rest of the trip. Though the "disabled for rest of the trip" bit can be trivially worked around by shutting down and powering back on, this seems to be better than what you mentioned in immediately shutting down the system while still driving.