Evidence from Europe and Asia shows that this is probably wrong. People in those areas strongly prefer high speed rail for trips that are less than 3-4 hours long, and begin to switch over to airplanes beyond that.
We're right back to "remember how big and sparsely populated the US is." 150mph in three hours is good for inter-city transportation in the Northeast, but a lot of other places would have trouble justifying the cost.
And that's nothing compared with what a truly high speed train would cost to implement here.
Again, that's a great reason not to build HSR in Iowa or the Dakotas. But if you look where the population centers of America, this excuse begins to fall down. A huge percentage of America lives on the coasts in fairly dense pockets, far denser than many countries with existing HSR.
High speed rail generally goes a bit faster than 300km/h. At that speed a lot of things are less than 4 hours away. Chicago is a bit less than 4 hours from NYC at that speed, as is Seattle from San Francisco. San Francisco to Seattle is obviously not a great candidate for a high speed rail line because it doesn't pass through much of interest, but it gives a good sense of the scale.
And that's nothing compared with what a truly high speed train would cost to implement here.