If a train can get you there faster than a plane people will use it. The same ultra-light rail I posted to this list about Cybertran that can substitute for buses ( http://www.cybertran.com/ ) has a high speed version that move up 150 miles per hour. It is much more expensive than the city transit version, but much less expensive than conventional bullet trains. Like the city version it is a mixture of on-demand and scheduled service. (On demand when traffic is light, schedule when traffic is heavy and you will a train every 2 minutes or so in any case.) Like PRTs the system is driverless, computer run and scheduled on the fly. But because it is more passengers per vehicle than PRTs and uses conservative off-the-shelf technology the cost is much less.You get a lower priced train that can run on conventional track when available or on special, less expensive track where new track needs to be built.
For distances below 500 miles (not 200) a 150 mph cybertran can get you point to point faster than 600 mph - (the train is ready to leave within 2 or 3 minutes of when you are, does not have idle waiting for a runway to takeoff, does not have to circle the destination airport waiting for a runway to land, and then idle again waiting for a gate to open). Because you are still talking trips of less than 4 hours cybertan will not need the extensive service Amtrak has - sleeper cars full fledged dining cars. But like current Amtrak it can have bathrooms, decent food and water - and a hell of a lot more legroom than an airplane.
This would make Cybertran much more energy efficient that a conventional short plane trip - especially since a short plane hops consume much more fuel per mile than long plane hops. (Take off and landing are really big fuel consumers in a flight . Just like stop and go traffic in a car is less fuel efficient per mile than a long steady drive, a short plane trip is much more fuel consuming per mile than a longer one.)
Cybertran strikes me as a perfect example of both the strengths and weakness of capitalism when it comes to technology development. Cybertran was a spin-off of military nuclear research - one of the big engines (and one of the most evil engines) of capitalist development. It was originally conceived as way to move stuff around the a huge laboratory campus. In spite of the source it is a truly magnificent technology - socially responsible on a huge number of level, and very practical in it's use of off-the-shelf parts that implement an extremely radical concept in a very conservative way. But it requires social deployment; like any rail system system it requires a large scale collective decision - essentially a decision by a state. In short capitalism can develop it, as a side-effect of other awful developments. But it would require massive pressure from the a left side of the political spectrum (something that really does not exist in the U.S. right now) to deploy it.
By the way - replacing short haul planes with rail would have another advantage. Although short-haul planes account for only a small percent of the miles traveled by air, they account for a hell of a lot of use of run-ways, and traffic control resources (over half the trips -which does not mean half the use of runways, but is not that far from it either). Replace plane trips under 500 miles by a rail system, and those flying longer distances would not have to spend nearly as much time waiting in the planes while they idle, or taxi waiting for takeoff, or circle the airport waiting for a landing runway. So it would improve the fuel efficiency of the long haul planes as well. You would relieve the overcrowding in most airports, and also avoid the expense of having to expand existing airports and build new ones for some time to come.