I should think that any airport with radar does not need an NDB for the missed approach, because they would vector the traffic.
You can bet Heathrow is never going to send somebody back to the NDB. Especially as, I also bet, a % of the airliners landing there right now don't have an ADF... not that it matters because the NDB will be in their GPS database.
I don't know how these things work when it comes to official navaid planning but my guess would be that NDBs will remain as approach fixes, because the alternative is a marker beacon and those have mostly vanished in Europe. But with DME you don't need an approach fix, and almost every ILS has a DME.
Is a DME cheaper than an NDB? It is probably similar, and much more useful.
I cannot believe that people flying to N Sea platforms think the NDB will be a good backup. If you get a TS nearby, the needle will point just about anywhere. And there is no "valid" flag so it is a case of "if the needle agrees with the GPS, fine, and if it doesn't agree, you ignore it".
So that leaves just the missed approach case. This can be dealt with (on the approach plate) by intercepting some VOR radial and flying a hold there - flying an "enroute" hold around some holding fix defined by a VOR is standard IR staple diet
The VOR could be miles away; nowhere near the airport, so the airport isn't paying for it.