There are many 20,O00 + hr C 172's and C 150/152's still earning a living at flight schools.
Back in the early 1980's Cessna bought a C 172 that had over 30,000 hrs, all low level pipeline patrol. They completely disassembled and inspected every part of the aircraft to see what shape it was in and essentially found no issues.
Corrosion is the big killer of light aircraft, particularly for those not kept in a hangar and not regularly flown.
One of the Convair 580's I fly has more than 98,000 hrs and 156,000 cycles......