At the end of the day, the economics will be impossible to ignore, even for the Pentagon. We better hope the economics become impossible to ignore, else we could be in a world of hurt when China or someone else suddenly shows up with squadrons of drones and perhaps robotic soldiers.
I have little faith in the Pentagon to think ahead. The brass love their toys, eg big fleets of big ships, big squadrons of big, expensive airplanes, etc, all of which require large numbers of troops to operate , etc, which means large numbers of officers are needed to manage it all. They are little different from bank CEOs, where we know the only thing that correlates to bank size is CEO compensation.
And like big banks, big ships and planes are very vulnerable, only there will not be a Fed to bail them out. Our surface Navy could be decimated in the first day or two of a real war with someone with modern weapons. We were always wondering where the Japanese fleet was in WW II. The Chinese know precisely where every single one of our ships is, in real time.
The world's militaries have a long and undistinguished history of being ready to fight the last war. We may actually have a big advantage with drones, because we may not be raising a lot of athletic, fit kids who are good with firearms, but by golly, we have a lot of them who can sit all day and play video games.