I've had Sequoias for just over a year. I had the first one replaced due to a defect in the bungee leg strap and the stitching coming apart on the bridge. Petzl sent me an new one and a ring for the bridge. It didn't make a difference to how quickly that bridge lost it's stitching again.
So, rings have never been an issue and I would expect them to last as long as the saddle is in use barring direct impacts. I tend not to replace saddles frequently so it may be around for 4 or more yrs. I may get a newer, cooler one before I need to retire this one!