Everybody assumes that oil prices are going up. However, there are several large effects that could cause the price of oil to decline.
1. Economics predicts that the price of something will be the same as the price of its cheapest substitute. For a long time, fossil fuels were the substitute, keeping the price of renewables & nuclear down to unprofitable levels. However, renewables, storage and electric cars are all rapidly decreasing in cost, depressing their prices and the prices of their substitutes.
2. Carbon taxes or other similar schemes are looking more likely in the future. They shift the demand/supply curve, causing fewer barrels to be sold at higher prices, but the price doesn't go up enough to cover the full increase, leading to depressed prices before the tax.
3. Economics says that the price of a commodity is the same as the marginal cost of production. In other words, the highest cost producer of oil that meets current demand makes $0 in profit, all lower cost producers make >$0 profit. If demand is low, then that marginal cost is $10 Saudi oil. If demand is high, then that marginal cost is $100 Canadian oilsands oil. So if demand drops because of climate change mitigation and/or renewable substitution and/or electric vehicle substitution, there is supply of lower cost oil, meaning prices can drop.
4. We're not running out of oil, we never have been. As mentioned in #3, the price of oil is the marginal cost of production. Anything that costs more than that price isn't counted in reserves because it's uneconomical to extract. So by definition we always have almost no reserves and never will have.
There are trillions of barrels of oil in the Canadian and Venezuelan oil sands alone that aren't counted as reserves for this reason. We're less than 2 price doubling periods away from making this economical, keeping a fairly low ceiling on prices.
And of course technology marches on, continually decreasing the price of extracting that oil...