This is how Internet conversations get off track (snicker snicker).
@TrimetWESFan1003 mentioned the HARTFORD line and the Valley FLYER, nothing about the HEARTLAND FLYER... The Valley Flyer runs on the Hartford Line along the Connecticut River (the same route as the Vermonter) from New Haven to Greenfield MA, no where near Texas or Oklahoma. It is all single level and there are almost certainly clearance issues for Superliner cars, including NEC cat clearance in New Haven. So the problems and opportunities for these lines are very different from the Heartland Flyer, which is currently all Superliner equipment.
It would be great if Amtrak could find common equipment that would work in both the east and west, but I think that is very unlikely and is, for the next several decades, a pipe-dream. Amtrak needs new and additional equipment NOW, not in the 2050's.