Well, no, not necessarily. Existing tech might well replace oil in all of it's many uses long before the stock runs out. What happens is, the oil doesn't just all disappear at midnight, see. It starts getting scarcer first. The price goes up.
People get more serious about finding ways to do without it.
The government finds a better way to kill people than napalm. People start making things to last again, to use less plastic. If gas gets expensive enough, those monorail systems will make sense. They'll get built and people will use them. Plus, the free-market doesn't exist anywhere in the world.