Robert B,
80-ish% of accidents are still pilot error. If the age of the fleet was a causal factor in accidents, the accident would be rising over the decades as the fleet ages, when in fact the opposite is true.
Re: engines. Here’s Paul B’s excellent AvWeb piece on Why New Engine Ideas Rarely Succeed: https://www.youtube.com/watch?v=_k1TQGK3mZI
As a retired Air Force pilot and current airline pilot, I can tell you we practice BOTH maneuvers AND scenarios. In the single pilot GA world, I would argue the emphasis SHOULD be on maneuvers, as that is what the accident data suggests needs improvement. The reason scenario training is conducted in multi-crew, transport category aircraft is that the systems are much more complex, the environment more dynamic and challenging, and crew resource management must be trained/practiced. This type of scenario training requires expensive, full motion simulators and is not practical for GA. What types of scenarios are you suggesting GA practice?