[Blue Jays]

You make excellent points. A cautious and conservative approach would be to utilize high-speed trains for inter-city trips up to about 500 miles or so.
This could help relieve airspace congestion and boost safety while keeping people moving rapidly on a regional basis.
The trains need to be comfortable and in the 150+ mph speed range. This would require suitable rail bedding and durable bridge crossings.
We live in interesting times and we have to ensure our transportation capability remains robust.

[Nepeta]

We live in interesting times and we have to ensure our transportation capability remains robust.

In some places, I would think a high speed roadbed could be constructed parallel to the interstate highways in places where there is plenty of land around them. Tying these routes to both the air and automobile systems makes sense. Corridors of unconnected rail that only slightly reduce travel time makes no sense at all, which is what Fearless Leader is proposing.