Bottom bracket lifespan? Indefinite if serviced at appropriate intervals. Like the Sugino cups and spindle on my 1973 Gitane. Fresh grease and balls roughly yearly.
OTOH, I've seen cartridge BBs fail after a few weeks, when the owner decided to wash his bike with a pressure washer, or drive in the rain at highway speeds with the bike on a rack. Or in the aftermath of a century charity ride in the rain.
Remember that although modern cartridge units keep water out better than the old-style cup and cone units, they also keep water in. And when water does get in, they are difficult to impossible to service.