When we run out of 'oil' or the price at least runs up to stratospheric levels, the tar sands in Canada will become economically viable to extract. It's not likely to take long for US industries to make some sort of deal and start 'refining' (messy as it might be) when the price is finally high enough to support the business. The reserves in Canada's 'tar sands' (or 'oil sands') are estimated to be larger than Saudi Arabia's crude oil reserves.
http://www.energy.gov.ab.ca/com/Sands/default.htm
http://ffden-2.phys.uaf.edu/102sprin...ects/M.Sexton/
And even if this gets used up, there have been all sorts of clever processes tried over the years to make 'syntheitc' fuel oil, including some remarkably successful processes developed in Germany during the WW II shortages. Like the tar sands, price compared to the easily available form is all that keeps these processes from being used. So it seems much more likely that we'll have to give up oil burning due to pollution before we actually run out.