Not to mention that the shale oils energy required to acquire and refine is quite high compared with the energy that it provides as a petrol. Shale oil is definitly an option energy wise, just not a wise energy option.
In order to be profitable the cost of oil has to be over 35 dollars a barrel for shale oil to be worth refining. We have passed that price long ago. Our problem is more one of not building any new refineries not a lack of fossil fuels. We will have a new source of fuel I have no doubt long before we run out of fossil fuels.