I always fail to see the market there. Why is it superior to the car, considering the higher costs for fuel, that will be unavoidable?

It depends where you live. I regularly make a 35 mile drive to a place that's only twenty miles away. A vehicle that used 75% more fuel per mile than my car could let me make the same trip in almost half the time for the same amount of fuel.

Market is where land commute takes time. Eg., in Bay area, there are lot of people who commute from South Bay to San Francisco. Slow traffic is common during peak hours and it is frustrating. I see this area as one of the best places to try local air-commute.

It would add the third dimension to the commute space. Like the fast-lanes in freeways, lanes could be formed by altitude.

I think a far more likely solution / scenario is that we'll have cars that drive themselves. It'd also be a hell of a lot safer.

  "unavoidable"

:-|