There has been a lot of talk about lack of capacity for food in the cafe car, but this is not quite the big issue that many think it is IMHO.
First, a big part of the issue isn't capacity to store cold stuff; but rather simply failure to put enough into the cars in the first place. This is the fault of both Amtrak and the commissary with their rather conservative approach to not putting too much food on so that there is little to return and therefore little chance that anything spoils/reaches expiration date before it gets sold.
The Maple Leaf has always been a big problem, it often runs out of food on the return trip to NY from Canada. I always thought that it was a lack of capacity. A lack made worse by the fact that Amtrak must leave 1 fridge and 1 freezer empty at the border going north so that the VIA Rail crew has a place to put their stuff. I was dreading one weekend when my mom & I were returning from Toronto because it was a holiday weekend and I figured that food would run out even earlier than normal for this train. I even advised my mom that we needed to eat both lunch & dinner early to try to maximize our available choices. In the past I'd seen the Leaf cafe run out of pizza by the time it got back to Buffalo, or shortly thereafter.
I was greatly surprised to find out that we still had pizza as a choice by the time we got to Albany.
And most other choices for lunch dinner will still available too. On one trip in the past, I had breakfast for dinner, as that was the best choice left that year. But not this trip!
Being we were in BC I started chatting with the attendant when she wasn't busy and learned that the reason we still had food was because she had ordered extra from the commissary knowing that it was a holiday weekend, Labor Day, and she knew that she would sell more food than normal. And she was right! We did run out of many things by the time she closed up approaching NYP; but this smart & excellent employee had played things smart and had many happy customers simply because she took a bit of initiative.
My point in that long story is of course the simple fact that the storage is there! The problem is how much food is being loaded onto the car.
Second, as part of the Diner-Lite conversions, one of the things modified for the Amfleet II cafe cars was to add even more cold storage.
So while I'm sure on a busy train that they still might run out of things, especially if one misjudges what will be the most popular item, I don't think that Amtrak needs to be thinking about putting extra fridges & freezers in baggage cars or sleeper cars, or any place else. I think that the bigger problem with running out of things is simply how the car is being stocked by the commissary and not the cold storage space.
If one attendant can make the food hold out by requesting extra to go from NYP to Niagara (short 1 & 1) and back then there is no reason for the Palmetto to ever run out of food as that run is about the same length. And the Palmetto can restock in DC; the Leaf has no place to restock anymore.
Heck, I've seen crews run out of things on the Auto Train's cafe. Those Superliner cafes have even more storage than the single level cafe cars do. They can store enough to go two nights and three days on runs from Chicago to the west coast. So how can they not store enough food not to run out on the overnight AT?
Again, the problem isn't storage, but rather the way too conservative loading of the cars! And with the loss of the diner on the Star, Amtrak & the commissary need to double down and then some!