Driving without it will likely result in:
* Loss of power steering: Making the car extremely difficult and dangerous to steer, especially at higher speeds.
* Overheating: The engine will overheat quickly without coolant circulation. This can cause serious and permanent engine damage.
* Loss of electrical power: The battery will drain, leading to failure of lights, power windows, and eventually, the engine stalling.
* Failure of air conditioning: A minor inconvenience, but not a safety hazard in itself.
In short, driving without a serpentine belt risks significant damage to your car and creates a serious safety hazard for you and others on the road. If it breaks, pull over to a safe location immediately and have it replaced.