Ok, let's all admit that most aircrew jobs aren't that difficult (please note the 'most'). And what were half our NCA before they went aircrew? (Pre WSop, of course). Yep, serving personnel. And what makes good aircrew? Personally, I'd suggest a basic level of aptitude, with a bucket load of experience thrown in on top. Of course we can train just about anybody to fill a FE position, same as we can take most recruits and turn them into NCA. There is a different perception/perspective towards aircrew systems operation and techie operation, but that's surely due to the background of their training and work experience, and it's hardly insurmountable. And is it even a major problem on the larger ME aircraft, where there is less flexibility in operation and systems management (drills are FRC driven, and you can't go around pulling CBs as they impact on multiple systems - remember the airbus with a broken back on its ground runs?). With reference to the old airline manning, with a new pilot operating the 2nd officers position, that worked fine, and I bet they never tried to engender a FE's perspective. So can we train techs to fill FE positions in the future? Of course we blooming well can. Will they be as good as an experienced FE. Nope. Will they be as good as a newly qual'd FE? Probably not far off. Will they gain airmanship? Course they will, just like all new aircrew do.
Mind you, one thought. Has anybody even wondered if the techs will want to fill in for a few years?