Rotorboy, I don't think it's true that VOR's are being abandoned while NDB's are being maintained. A look at the Jepp NavData notams shows a long list of NDB's OTS or decommissioned, few if any VOR's. LOM's are being decommissioned at a fair clip.
Shy, GPS does have an alerting system - that's what the RAIM alert is for. However, I don't see what NDB's have to do with idiots drawing up & flying their own approaches. Sounds like you (or the CAA) want to do away with GPS just because someone abuses it. N.B., pilots have flown unauthorized NDB approaches far longer than GPS, since the NDB's have been around far longer. Removing ADF receivers from offshore helicopters, or EMS helicopters, has nothing at all that I can see to do with this.
If your operation requires an ADF, by all means keep it. But in another part of the world, where it's of no practical use, why argue for keeping it? Do what you need to & let others do the same, is my opinion.