The guy who said 50 years said that was based on today's technology. And he also said that estimate could be extended as new oil extraction tech comes online.Well, until I see evidence to the contrary, I'm going with the consensus of the 50-year prediction, hoping it's wrong that we won't find a replacement in time.
One thing we know with absolute certainty about the oil industry: they are always inventing new technology to enhance oil exploration, extraction, and production. There is no question that new and unforseen oil extraction technology will be developed in the next years.