This dining change has been discussed in many threads for a while. I have 3 trips planned on the Silver Meteor in October and received 3 emails. My guess is that if I phoned Amtrak and wanted to switch to the Silver Star, they would permit it. However, even though I am not wild about the new menu, I like the idea of the Sleeper Lounge, unlimited non-alcoholic beverages and one alcoholic beverage. I believe the flexible meals are better than the cafe car offerings. The timing of the Meteor also works better for me - especially since on one trip, I will be connecting to a Chicago bound train.
I believe the breakfast sandwiches will be heated. If you are displeased, call Amtrak. I do not know if a "regular" telephone agent will be able to assist you with a refund or you will have to talk to Customer Relations.