For flights significantly less than 1000 miles, I think current jets are ill suited. What may be needed are large wing-span jumbos run by turboprops (4 or more) that cruise at less than 20k feet, and at about 300 mph. Luggage would be limited to carry-ons and people would mostly stand rather than sit. This would cut the per person fuel price by 2/3rds, and would be a lot cheaper and more comfortable than driving the same distance. There just aren't enough rails going in the right directions to take up the slack. Also it would be safer than exposing oneself on the highway.

HOG