Gotta say, Michael, that's nothing but a bunch of excuses.
1) Fitness: If you are fit, you take it once a year. Unfit, multiple times. That is called incentive. Make it part of the certification class. Not exactly undoable.
2) Assessors: As described above, ONLY at a single match involving an official with multiple, recurring strikes on post-game evals by coaches. In other words, rarely.
3) Nobody asked for ANY of that -- just people who meet a minimal fitness standard, are willing and able to keep up with play, and make an effort to get it right. Answer: YOU CAN!!!
4) The "threat" of not having enough officials is a smokescreen. My guess would be, develop a level of pride and consistency in training and evaluation, and you might get MORE YOUNG PEOPLE into officiating. People who want to be the best want to work with the best.
In summary, I would GLADLY give my time on a regular basis to meet with assigners, evaluators, etc., in an effort to develop a better system. What we have now is limping along. We CAN make it better, if established officials (such as yourself) would get on board and stop with the litany of excuses.