I like the idea, but as usual, it’s the DETAILS that count.
Nearly every aviation publication warns against little-utilized airplanes. The engine is especially vulnerable "other than a look see of the engine, ". Those are the aircraft I would worry about the MOST–as opined by so many aviation engine experts, the build-up of acids and moisture in an underutilzied engine is far more damaging than putting on hours. Most aircraft dealers (myself included) won’t have anything to do with selling “hangar queens.”
Theoretically, you could have an aircraft that has been sitting for 4 1/2 years–then flown, “annual inspected” (NOT) and sold.
Don’t get me wrong, I LIKE the concept–but need to adjust the details. Perhaps something like “a minimum of hours AND time between flights” could be adopted–with inspections not to exceed ___years." It should also be limited to simple airplanes–a complex fuel-injected aircraft should not sit very long.
You are absolutely correct–a simple fixed-gear non injected airplane flying a minimum of 40 hours a year could alternate an inspection annually between the engine and airframe–(you wouldn’t believe the things we find in airframes that are not flown regularly), effectively drastically reducing maintenance and inspection costs–and freeing up mechanics for aircraft that DO fly more.