In a market economy, we never actually run out of a resource; rather, the price rises gradually in accordance with increasing scarcity and cost of extraction, m

In a market economy, we never actually run out of a resource; rather, the price rises gradually in accordance with increasing scarcity and cost of extraction, making alternatives more cost-effective, increasing the reward to researching alternatives, and pushing the use of that resource into niches where the cost doesn't matter as much. Examples of this would be guano (replaced by saltpeter and then by the Haber process) and whale oil (replaced by petroleum).