I doubt that’s going to happen. There’s enough shale oil in North America recoverable using current technology to sustain world petroleum consumption for 15 years at least. The only reason it hasn’t been developed is people are gun shy after losing a lot of money in the 70’s thinking peak oil was upon us.

Even without any alternative energy source development – not that I have a great deal of confidence in those – oil isn’t going to deplete fast enough to be ‘prohibitively expensive’ in 10 years.