High Spirits - there will be those who are happy not to progress beyond Sqn Ldr for personal (and professional) reasons and spouse income/career will probably be a major driver. But I think that a lot of driftwood will be depositied in the shallow estuaries of main stream posts.
Grumpy - I share your concern that the duff jobs will be left to the duffers, and that the choice will be substantially reduced. I enjoyed my tours in Town and I would urge any officer from Sqn Ldr up to not to be put off by the naysayers about MB tours. But from 1 Sep, these will largely be the province of the Thrusters.