If you are driving your car and your timing belt broke, the results can be both dangerous and costly. Car Timing belt advised replacement intervals can improve your engine life & save hundreds of dollars too.
Timing belt cost is not so high to avoid replacement. If you can hear noise and observe bad timing belt symptoms. Driver must not delay it. The serpentine belt is different from the drive belt, You can still drive with broken serpentine but driving with a bad drive belt can be dangerous in the way
In an interference engine, If your engine is on and if it breaks, It will stuck on different parts of the engine. Because it is driven by the crankshaft and operating camshaft. It shall stop one or both of them. Sometimes you may need to rebuild the engine too. The car can suddenly stop on highways.
In a non-interference engine, you will not face any loss with the breaking of other engine internal parts. Subaru & some other diesel engines are non-interference. Always consult your mechanic about your engine.