The world will need oil for a long, long time as there is no single technology that can replace it. In addition it will take a lot more than 20 years to implement any partial replacement technologies. As a result, the oil producers will continue to be wealthy even as the amount of oil produced decreases over time.
Israeli forces demolish illegal houses, power infrastructure in Palestinian village Aqaba (Haaretz)
from the article: After Rice / Creeping back to the unilateral