with a falling oil price they may be queuing up to return........
I'm sure you mean this tongue in cheek, but the dear old MPA threads do get spraffed to death, so allow me a semi serious reply.
Almost everybody that did this job has gone forever for a multitude of reasons, which need not concern us, but age alone would rule out the vast majority being re-recruited and retrained.
So, in the event, we ever need a "workable" number of crews again (8-12, with 1 or 2 in the training role, like one sqn with a training element) they would need to be recruited and trained from scratch. Presumably by seedcorners and the outfits still training other types or rear-end aircrew.
I'd suggest you can draw two conclusions from that:
a. Whatever, it will take 3-5 years to re-establish an operational capability from the go date.
b. The window for an RAF only solution closes when the seedcorners leave the building. After that, the RN will have to be part of the crew, because the RAF will have lost its ASW expertise for ever.