It would probably be cheaper for Cessna to buy up all the old airframes and scrap them. Manufacturers have been known to do that. Do we really want that? There are some perfectly good 50-yr old airframes out there that will go on indefinitely. Don't forget, certainly in the case of the PA28, Piper didn't expect it to last more than 10 years.
Our checklist for our 50-yr old PA28 includes an Emergency section. The most common emergency we train for is the total loss of engine power, the training in the UK is known as PFL or Practice Forced Landing, exercise 16. Having established at the best glide speed and chosen a landing place, we then go through determining the failure cause. I teach working from left to right across the cockpit, which should work in most light aircraft. I expect students to follow this 'workflow' whilst flying the aircraft. I had one student the other day whip out the checklist and start reading from it. I cancelled the exercise and we went back to have a discussion on single pilot operations and how all airborne drills need to be done from memory. Oh dear, bad mark for me for not teaching it properly; I thought I'd briefed pre-flight adequately, obviously not.
TOO
ps. Every day is a school day. I've had to look up what 'deontologically' means! A bit tautological in the above context...