Kunze plans to distribute ceramic tokens around the world to everyone who either funds, contributes to, or advises on the project. Every 50 years, starting in 2070, he says, holders will meet to keep the memory of the capsule alive and to discuss if it needs to be reopened
The problem with this is that if there are enough people around that remember about this and have the spare time and means to go there an dig an opening again, then it's probably not needed because society still exists.
If a some global catastrophe happens that wipes out much of our our modern records and knowledge, then "Oh hey, there's some good books under a mountain in another continent" is going to be pretty low on the list of things that's preserved through oral lore.