The US Air Force has a keen interest in SpaceX with its possibility for rapid launches of reusable rockets for this and other reasons. SpaceX is hoping for less than one day turnaround with its most recent design (block 5) of its Falcon 9 rockets[1]. This design is already flying. With enough GPS satellites in storage, they could all be replaced in a week.
I imagine that the military is going to be much more effective without having to use workarounds. I doubt current munitions have extra weight dedicated to backup gyroscope navigation (could be wrong). Launching two dozen satellites has to be easier, faster, and cheaper than replacing the whole military's munitions stockpile with less effective weapons.
[1]https://spacenews.com/spacex-targeting-24-hour-turnaround-in...