The way things are going with regard to Rear Crew training, it might be that the only "aircrew" in the future will be the Pilot, with personnel filling flying duties in the other roles in the aircraft based on specialist knowledge from ground trades. Harks back to the early days of the RAF, where the chap that fired the guns was an armourer who happened to be flying that day. It'll save on pay and training costs; the Bean Counters will love it even though it will mean a drop in effectiveness.