My sister and B-in-Law are FL residents. They 'summer' in Maine for a brief spell. They gave the AT two shots. Never again. And they paid for sleeper accommodations, too. They detest the drive on I-95, but now considering the expense for the AT, they simply drive shorter legs, take more breaks, etc..
On my last visit with my sister & her hubby we talked again about the AT....and that it would have even greater appeal were it to have a terminus farther north....northern NJ, e.g.. However, the current AT basically is a two-train operation....one set heading north while the other set heads south. If you tried to stretch that route farther, you'd need MULTIPLE trains, since the trip and turn-around could not possibly be done in one 24-hour stretch.....especially with the usual delays that STILL exist. Couple that with the already busy-and-then-some D.C.-to-NYC/Boston corridor, and I'd say it'd be worse than a nightmare in scheduling. Accidents, equipment malfunctions, construction zones, weather delays, etc., etc.,.......it's not a pretty picture in my mind.
Conceptually for this country and its expanse between seasonally lucrative sites, it makes sense superficially. From a business perspective, though, I doubt that prospective ledger sheets would be very encouraging to investors. Remember, even the current AT doesn't own the track and all of its concomitant expenses. It may have some scheduling priorities, but since it shares someone else's track with someone else's trains, those priorities can be meaningless if there's a 'snafu' among the other traffic. And that, BTW, is what happened on my sister's last ride....resulting in some expensive trickle-down defaults on other portions of their northern post-AT trip.
Ah, well, the dreams and debates will continue, I'm sure.
KD