Let me draw that out further. I hate doing this kind of speculations, but lets consider the following:
1) The Superliner I cars are reaching the end of their lifecycle, and would benefit from replacement.
2) The Amfleet II cars are also indicated to be nearing the end of their lifecycle, and would benefit from replacement.
3) The Amfleet I cars were next to be replaced on that list.
Further, it would not be difficult, in my opinion, to reconfigure the Russian Rail design cars to have a center aisle with 16 roomettes- the rooms appear to me to be 2 meters wide, so longitudinal berth is likely doable, using the same window design as the Russian car.
This would allow you to create a pair of cars consisting of a 16-roomette car with 2 restrooms, a shower, and an attendant's room (as configured for the russian train), and a 6-bedroom (two berths and a bath), one-handicapped room, and 2 family (four berths, no bath), two bathrooms, and a shower. This combined car pair would give you 16 roomettes, 6 bedrooms, 2 family rooms, and a handicapped room, for a total of 54 passengers; an increase of 10 over a Superliner, and a relatively minor decrease of 3-per-car average over a Viewliner.
Diners, lounges, and coaches are of course in the bag for that sort of thing. Lounges and diners would be a straight replacement sort of thing. For a Superliner coach, you would need 3 60 passenger single levels to replace each one.
To replace the Superliner I sleepers (70 originally), diners (35 originally), lounges (25), and coaches (135, iirc), the Amfleet II coaches (125) and lounges (25), and the Amfleet I coaches and cafes (call it 420 coaches and 80 lounges), you would need:
70 Bedroom Sleepers
70 Roomette Sleepers
305 LD coaches
50 LD lounge cars
35 dining cars 530
420 short distance coaches
80 short distance lounge cars
1030 Total Cars
Do you really thing that if Amtrak managed to make a coherent order for replacing the cars, consisting of 1030 cars over a 10-15 year time frame at say $3 mil a piece average, for a $3.1 billion order, Siemens would be unwilling to bid, because of the difficulty of redesigning the interior wall structures of 70 of the cars?