In some places rails to trails makes a lot of sense but a lot of the lost right of way would be much better used for intercity or interurban lines.
I think this is true of rail in general, in large cities, and between large cities in heavily populated areas (northeast, Texas, Florida, Ca, etc) passenger trains make a ton of sense, in much of the country flying or driving makes a lot more sense though.
I’d never take the train between Vegas and SLC because I can relax and drive it in 5-6 hours, I can’t wait for the train to LA though because that drive is non stop stressful traffic and can be anywhere from 3.5-9 hours.
To me trains only make sense where it’s a less stressful option than driving and/or flying.
In FL, with many large metro areas relatively close together it makes perfect sense, in CA with many large metro areas relatively close together it makes perfect sense, in the northeast, in Texas, along the coasts, it makes perfect sense. In most of the midwest, the west, the south, etc it makes no sense compared to flying or driving.