hmm, it will be nice to speculate the actions of the gas company in the near future, when hybrid cars dominate and the demand for fuel goes down. Will the price drop to encourage fuel purchase or will it inflate just so that they can survive? Well, it will be pretty bad if the cost of fuel actually go up because of this as we will still need fuel after all; it's not as if we can totally do without them and hence they'd still have some control over the gas market.
Given this, wouldn't it be really ironical if car companies invest so much into increasing fuel efficiency so that it'll be more financially attractive (other than being more green) and in the end, consumers still pay the same for gas, and more for those who stayed with solely gas?