What serious person is pitching LA -> DC as a city pair for HSR?
The best routes are the ones that replace short-haul flights that are currently really inconvenient in terms of driving and rail service. A route like New York to Toronto would make plenty of sense, where you have two major population centers that are very close together, but a huge headache to travel between by rail today (at 12+ hours total on Amtrak and Via Rail).