I, too, have three 3rd gen Smiths, all 9mm and they're all in my carry rotation. The oldest gun is almost 20, the newest less than 10 years old. Frankly, I believe they'll retire me rather than the other way around. True, any tool can fail, but in quality tools, failure is rare. Will an S&W Bodyguard .380 or Ruger LCP go 20,000+ rounds? Somehow, I doubt it. Are they designed to last that long? Will a 6906 go 20,000+? Yes. Is it so designed?

To paraphrase Dasheill Hammett, most guns don't break; they get broken --- either through abuse or neglect. For example, I have a 40 year old Colt Combat Commander .45. I bought it used, but I've never replaced a part other than the recoil spring. It shoots as well as the day I bought it. I also have my grandfather's Woodsman. The gun was made in 1933 and as far as I know, it's never had a single piece replaced. It'll still pop a squirrel at 25 yards if I do my part.

Now, granted, there's a difference between a .22, a low pressure .45 and a high pressure 9mm. A well built pistol should be able to carry the load for decades and I've never heard anyone describe the third generation Smith & Wessons as anything less than well built.