Yes indeed it is very sad to hear only about 10% of the NDBs OTA compared to the 80s - the beginning of the end was when the wonderful MARINE SUB-BAND (285-325 kHz) containing cool sequenced lighthouse (and other locales) beacons were ongoing, as well as single marine NDBs were OTA.
DGPS took over for a while there but now is largely gone, temporarily re-opening up former NDB frequencies and DX formerly covered by the various DGPS transmissions. JUst for a spell...
Yep, by 2030 LW is going to be strangely empty (if the ICBMS have not flown and blown yet) - I suggest counteraction: - A TAKEOVER by hoibbyists (like the HF beacons) abd personal NDBs should happen! Perhaps a minority view and a bit controversial, but this IS HFU and many here ARE into un-sanctioned (by the govt AHs) beaconeering, so WHY NOT, when the FAA and other avation-related NDBS largely vacate the band, just TAKE OVER the emptied RF spaces with experimental beacons of our own...
***QUITE FRANKLY THE USA REALLY REALLY REALLY NEEDS TO GET RID RID RID OF 90% of it's AMBCB overload/logjam of crap and crud-race-to-the-bottom transmitters/transmissions (commercial/advert-overload 75 percent crap adverts) on the declining and assinine AM band, thusly opening-up long-haul DX like the rest of the planet can now enjoy on the AMBCB (except in China which has become also just as log-jammed an AM dial like the USA go figure...) >>> make the stupid AM band more like the emptying-out LF NDB/BCB band, folks... maybe by 2050 or after the ICBMs fly... good luck...