Amtrak already provides some level of room service.
http://www.amtrak.com/servlet/ContentServe...79&ssid=352
From what I understand, if you are in the H bedroom, it is fairly routine for the SCA to bring meals to you if you ask.
I also understand that they will bring your meal to any room if you ask, but I could be wrong. It may depend on the how busy the SCA is. This may not be a rule carved in stone, but just a service.
Of course, you wouldn't want to require sleeper pax to eat in their room.
This would help thin out the diner crowd, but not deal with the issue of food available for coach. If the trains are routinely running out of food, then Amtrak needs to bring more food onboard at the start point. If there is not enough storage space, then maybe they could replenish the food down the line at another station, maybe after 3 meals have been served.