I think the most feasible proposal is the extension of Trains 391/392 to Memphis. That really just becomes a matter of capacity. Those trains already run with extra rolling stock to meet the insane axle count requirement. The downside is coming up with an additional Superliner train set.
Schedule is a problem with serving past Roanoke. You get unpleasant schedules at one end or another. I don’t see this as likely, but I’d be curious how the first state supported sleeper train would work.
The services between Louisville and Atlanta seem to be the most challenging between track conditions, the mountain environment, and not having a link to an existing service.
It likely wouldn't be a Superliner set. More likely is a piggyback order onto the upcoming corridor train order.
I don't see a state-supported sleeper train (though I wouldn't be
shocked if something came together...I think VA might be able to be talked into supporting something given the length of a putative Chattanooga-DC run, both in terms of time and mileage). However, Amtrak (or the DOT) working something up wouldn't be
impossible to imagine.
Edit: By way of explanation, Bristol-Washington is presently estimated at about eight hours one-way. Thats doable for a day train. However, on the old Pelican timetable, Bristol-Chattanooga was another seven hours. That is beginning to push the limits of a day train (if it can be achieved) and on the proposed timetables it would be arriving close to midnight (and departing at like 0200). Obviously, there's room to move this around in various ways (e.g. pushing the NB runtime north by like four hours, which would align with 66's schedule better), and once you extend to Bristol you don't have to add any new equipment (Bristol basically forces you to add a second set), so the incremental costs here aren't a complete disaster. Heck, you could even
potentially make it from Roanoke to Chattanooga with the same operating crew, though a crew division break at Bristol might make better logistical sense. The question is "How close can you come to the Pelican's timetable?"
One other thing of note - I realize that this is not likely to be a slam-full train like you get further north, but I do wonder at the state of buses and so on in that area. I feel like there will be more ridership than might be expected, if just because of a lack of alternatives along the line.