The idea of having food service personnel work a "step-on/step-off" schedule sounds nice, but I'm skeptical about it on a practical level. The issues of on-time performance are the first stumbling block. But it would still be problematic if everything is on time. If, for example, a food service crew finishes dinner service, including post-dinner cleanup, and gets off the train at a turnaround point at 11:00 pm, what happens if the next train going the opposite direction arrives at 2:30 am? Are they expected to sleep from 11:45 till 1:45, then get up to catch the next train, then sleep from 3:00 till 5:00 am, then open the diner for breakfast at 6 am. This would still require Amtrak to have sleeping quarters for the crew on both trains, plus the turnaround point; and it would guarantee about 4 hours' INTERRUPTED sleep at the turnaround. Try working that schedule.
As for off-train kitchens, I'm also skeptical. If it's decided that a schedule needs to be changed or a new train introduced, what happens if the contracted kitchens don't happen to be located in the right places? On-time performance would be an issue, of course. Amtrak would have to have a guarantee that the kitchen can supply the food at ANY HOUIR OF THE DAY OR NIGHT. And what happens if the train picks up the food and gets underway, and then the crew discovers there is something wrong with the quantity, or quality, or the specific content of the order? It's not likely that the dispatcher would let them go back to correct it.
Greater frequency on LD routes? Don't hold your breath.
Maybe there's a way to do these things, but I haven't figured it out.