I don't know how you could wear one out.
These are tough, tough, reliable guns.
If it were a cop gun drawn from a holster multiple times a day and the decocker (1006, 1066) flipped off and on multiple times a day for 20 years, the finish might get worn and sear release lever may wear out. The finish can be taken care of with a Scotch Brite pad and the sear release lever is a $2.50 part that S&W will repair for free.