Come on folks, an overnight replacement of Superliners isn't going to happen, it's virtually impossible to do. Just look at the slow phase introduction of new Viewliner 2s into service for confirmation. New replacement cars are going to have to be able to interface with the older cars, otherwise it will be impossible to walk the length of the train.
Trains sold as complete sets like Acela and Talgo are the exception. which might be why there's so much talk about buying entire train sets instead of individual cars. For example, the SW Chief requires 6 train sets for its daily service. Amtrak could replace a set at a time with a train with different floor heights while continuing to run Superliners on the other train sets. Instead of phasing in individual cars, they phase in whole sets. Otherwise, an entirely new design wouldn't work.
Trains sold as complete sets like Acela and Talgo are the exception. which might be why there's so much talk about buying entire train sets instead of individual cars. For example, the SW Chief requires 6 train sets for its daily service. Amtrak could replace a set at a time with a train with different floor heights while continuing to run Superliners on the other train sets. Instead of phasing in individual cars, they phase in whole sets. Otherwise, an entirely new design wouldn't work.