Southern ran an "inverted Crescent" until sometime in the 1970s in the form of the Piedmont Limited, but it was only ATL-WAS.
The biggest issue with trying to get additional LD service at the moment is equipment, followed by the fact that you could probably allocate another 100 Superlines, 100 Viewliners, and 100 Amfleets without making the existing trains "too long":
-In the East, the Silvers can arguably go to 18 cars, the LSL-NYP to about 11-12, the LSL-BOS could probably stretch to 6, and a daily Cardinal could probably get into the 12-car range before you start having severe platforming issues. You could also see a revived Broadway (either as a separate train or as an expanded piggyback on the Cap/Penny) and a re-extended Silver Palm/Palmetto.
-In the West, most of those trains could probably add a sleeper if the demand and cars were there. Ditto a coach. Beyond this, you start needing different mixes of food service cars (either an intermediate option or additional capacity becomes necessary).
Going down the list, let's assume that Amtrak were to stretch the LD trains in the East to their practical limits amid rising demand:
-Silver Meteor (4 each): 8 sleepers, 2 dining cars (one acting as a diner-club, the other as a full diner), 1 cafe, 7 coaches
-Silver Star (4 each): 8 sleepers, 2 dining cars (one acting as a diner-club, the other as a full diner), 1 cafe, 7 coaches
-Crescent (4 each): 8 sleepers, 2 dining cars (one acting as a diner-club, the other as a full diner), 1 cafe, 7 coaches
-LSL-NYP (3 each): 4 sleepers, 1 dining car, 1 cafe, 5 coaches
-LSL-BOS (3 each): 2 sleepers, 1 dining car, 3 coaches
-Cardinal (3 each): 3 sleepers, 1 dining car, 1 cafe, 5 coaches
-Pennsylvnian-CHI (3 each): 3 sleepers, 1 dining car, 2 coaches
-Shoreliner-through (2 each): 2 sleepers, 1 cafe, 4 coaches
-Shoreliner-BOS/NYP (2 each): 1 sleeper
-Shoreliner-NYP/WAS (2 each): 1 sleeper
Right there, without adding a slot anywhere (though requiring double spots, nothing not found in the "old days" back in the 70s), I've burned 140 sleepers before spares. On top of that, you're looking at 36 diners, 137 coaches, and a raft of cafe cars, all plus spares. Now, I do know that the consists might look different in their exact makeup, but my point is that Amtrak could probably triple their LDSL sleeper fleet and not need to add a frequency. Not only that, but a long Silver Palm would probably burn another 32 sleepers, so...again, not a single train is actually "added" but you're probably at 200 sleepers once spares, shopped cars, etc. are taken into account. Amtrak currently has 50.
Now, to be fair, if Amtrak was packing trains that long to near capacity, based on what we've seen about direct operating costs, most or all of those trains would probably be in the black on that account and posting relatively small fully-allocated costs (think CR of 75% or so on that front) and Amtrak would have a business case for adding those frequencies that isn't there at the present. Bear in mind that the ridership for this to work would probably be 175-200% of what it is presently (basically, the Silvers would be over two million riders vs. about one million now, the LSL would be getting up into the 600-750k range, etc.).