The problem is even natural gas would only be a temporary measure, a stop gag if you will, and we will never see if happen in our life times. The power of the oil and petroleum industries and countries is far to strong for them to allow the worlds largest user of crude oil to move to a different energy.
Also just as a side note natural gas is much cleaner for the environment than burning gasoline or diesel, and is of a much higher octane ratting (110ron if I remember right) along with having more BTU's.