If the world finally replaces it as the petro reserve currency. It won't REALLY go to zero, but our quality of life in the states immediately drops to revolution levels.
For as expensive as power and homes have been getting in the country, our ability to buy non-essentials like TVs, phones, furniture, etc for cheap has kept the populace mostly pacified. Make all of that shyt cost for us what it does for some other countries and we can't afford to live.