That's kind of already happened. The Moynihan Train Hall just opened up recently. I checked it out recently and it's quite nice, certainly much nicer than the old Penn Station. The next time you're getting off in NYC, walk towards the back of the train you came in on and then go up to the surface, and you'll be exiting in Moynihan instead of Penn.
Hawaii's interisland flights probably most closely resemble this air travel experience. Aside from Sunday & Friday fares that have a $30 premium due to work-week commuters, currently current week tickets are $49 and next week and beyond tickets are $39. And if you want to believe that's just a covid effect, there was a $29 special going last year right before covid.
Pair the process with chill, small-ish airports* and the hassle of flying is about as low as it gets for controlled commercial air travel.
Years ago, it used to be the norm to Judy show up 10 or 15 minutes before the flight.
* Obviously Honolulu is an exception, but it does have a separate interisland terminal.
I think it's kinda weird how very few politicians are talking about this.