I have a custom made columbus sl since 1987 maybe. No problems with him ever. And probably it will last long enough to be used by my kids in a few more years. So such a thing of a lifespan is so relative. For example years ago many italian bikes had failures in their tubes or lugs, since day 1 u knew the bike was going to last 2 or 4 years like for example atala's. A Miyata Dura ace i had (this model never came to the us) used to get craked in the middle of the BB after 6 months, all of them got the same issue so the solution was take the bike straight to a frame builder to get the BB reinforced, repaint and then the frame last forever, after more than 25 years a friend still have his. Alan's were famous for having issues in the their forks. Aluminum Vitus had similar issues and other related with bonding.
Now a days with carbon u can get lifetime warrantee from some brands but only a few brands deos that, for example Pinarello gives you 6 months i believe in their carbon frames, so no wonder why is hard to see Pinarello's moving around.
Thanks.