MARC: At least someone else is thinking about multiple New York - Chicago trains. All ways wondered why the old New York Central did not put on a City of New Orleans like day train between those two cities. Yeah, the time zone issue would make the eastbound very early leaving to get a pre-midnight arrival in NYC. Suspect that by making their premier trains night trains they did not have to worry about clearing maintenance to pass a priority day train. Regardless, this route, with its fairly large intermediate cities, cries out for some speed up and four trains each way: something like the current Lake Shore, early morning arrivals on both ends, late evening departures on both ends and a "day" train. Something similar on the old Pennsylvania Railroad route should also be considered, maybe with a split/combine at Cleveland for the western portion. Oops, I have gotten well off topic.
Now, back to the subject: If you want to be realistic about Dallas - Florida, serious money would be required for track and signal work regardless of route. Yes, Flomaton - Pensacola - Tallahassee would need signals, but possibly not as much true trackwork as might be thought. Right after SCL took in L&N considerable work was done on this line including major relay of rail and CTC "islands" at some of the sidings, although these have probably been taken out. As to bridge work, the biggie, the Escambia Bay bridge east of Pensacola wood trestle and draw span was replaced with a high level concrete structure. Don't know what else was done. As to going east from Dallas to Meridian then Montgomery AL, all the Meridian - Montgomery section has never been anything but an end to end trio of slow speed low traffic branch line. Major work here, almost certainly requiring some significant bridge work. East of Montgomery, the old South Wind / Floridian route would probably be better, but here again much work to get speed up and add signals. At least at Bainbridge GA, a right turn to go to Tallahassee could be done instead of going to Waycross GA before turning south. I am inclined to say the route shown is the best of the bad. It does give Dallas to Baton Rouge to New Orleans service, but by which route Shreveport to Baton Rouge? Two possibilities, the KCS which has never been signalled or UP's T&P-GCL combination.