Never. Their price will steadily rise as the easily-accessible sources are depleted, until it becomes uneconomical to use them. We'll likely see gasoline phas

Never. Their price will steadily rise as the easily-accessible sources are depleted, until it becomes uneconomical to use them. We'll likely see gasoline phased out for transportation by 2030-2035. Kerosene is still going to be used for jets and rockets for the foreseeable future; there are no good substitutes. Coal is already on its way out for electricity generation, and disappeared from railroads and ships about 70 years ago. Plastics are also here with us for the foreseeable future; they don't use much oil, and they give a lot of product benefits that can't be replicated with other materials.