Salesmen like Casey always neglect to tell you that as prices increase, proven reserves increase as well. That is because, by definition, "proven reserves" means economically recoverable. Large sources of oil that were not economically recoverable ten years ago are going strong today, and there will be more to come on line as rising prices and improving technology make them worthwhile.
Will prices go up? Sure. When have they not, in the long run. But we are nowhere near running out.