Norway, Canada and Germany operate quite well with around 5 crews
AFAIK Canada has been operating with 18 Aurora plus 3 Arcturus, Germany with 8 P3 and Norway with 6 P3 aircraft, not crews. In addition these nations tend not to send their assets off to solve the world's troubles to the same extent as UK.
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.
I am not sure just how much Air ASW expertise the RN will be able to bring. Judging by comments made by senior officers from Illustrious just before she went off on her final NATO exercise, this was to be a rare opportunity for the aircrews to operate in a major ASW exercise. The inference from this and other comments was that the levels of experience were low.
We used to consider that most second and third tier ASW nations would never achieve our levels of expertise because they didnt get the live submarine contact time. With the dramatic reduction in UK submarine availability I would guess that this assessment now applies to UK.