You are assuming that there are not millions upon millions of people who can't justify flying from Boston to New York due to the fact that the car trip (when you factor in arrival at airport 90 mins ahead of time) isn't drastically slower than flying.
I say this as a seasoned east coast corporate whore. Many, many business travellers are forced to just drive from New York to Boston due to the fact that the trip is 3 and a half hours long in a car. NYC to DC is about 3 hours 44 minutes by car. These are distances which are just short enough to make a company tell an employee to drive instead of fly, but long enough that nobody in their right mind would want to commute this way on a semi-regular basis.
Not counting Baltimore, the East Coast corridor has over 35 million people in the big city's metro area.
If the price of this service is expected to be similar to air travel, then I get it (SF-LA), if this is simply about selling speed for a premium price...... but I think this is really about doing it faster AND cheaper. If its efficient enough, this could lead to a decoupling of workplace from home location, the way telecommuting was supposed to.
https://en.wikipedia.org/wiki/World%27s_busiest_air_routes#U...