Another thing to add to all this is FAA has been steadily removing from service non-GPS navigation aids.
They are enhancing the navaids that remain. Greater range, and a documented network of airports serviced by ground based instrument approach procedures.
The shrinkage of total number of navaids concerns me from a rural support perspective but less so as a pilot. What does concern me as a pilot is even the MON navaids are having maintenance issues resulting in outages.
See AIM 1-1-8. NAVAID Service Volumes https://www.faa.gov/air_traffic/publications/atpubs/aim_html...
"documented network of airports" is a poorly worded reference to MON airports as distinguished from MON navaids.
Which is exactly why we previously had such a dense network: to provide redundancy in the face of inevitable outages.