Dad,
I'd take a bet that this is a sorta kinda nothing new contract. A number of three letter federal groups but specialized custom rigs from manufactures. How many bullet proof vehicles, usually secrete service to protect the POTUS do we have? Burbs have been most prevalent for many years.
That alone should help keep a factory up and running.
Reality for the 2500 demise, as noted by grit iirc. Others in past too. The 8600&9900 gvwr anything but a van truck is gone. Stuck with a rig up to 7500 factory gvw, or 11-13k gvwr now a days. I for one would be glad to get the equal chassis if the 1500HD, an 8400 gvwr pickup. Prefer and ext cab vs crew cab only option. Out the LD motors in them, but chassis, typical 8 lug running gear of the older 8600 2500. Great truck, decent mpg, power to pull a 10K trailer, payload for a family of 4-6 +fido, upwards of 1000-1200 lbs of payload for said 10K trailer. This truck is missing in today's line up. Be it a burb, pickup etc.
Marty