Trap One
I think we will come full circle on this. There are going to be very few promotion opportunities (compared to a few years ago) post SDR. There is now a recognition that specialists who wish to stay put are not 'low achievers' but increasingly essential to output. Those deemed to be fit for higher office will be 'picked out' early and moved on. Everyone else (the overwhelming majority) will be able to specialise and stay put (more or less) without the usual stigma.
It will also decrease the need for pointless Sec Duties!
As I see it there will be very few Posts above Sqn Ldr within 5 or so years and the majority will be invited to vacate at their first exit point from the contract.