Redundancy

Nephi was commanded to make a second set of plates for reasons known to the Lord and he wisely separated the care of those two records between two lines of caretakers—one the political and social caretakers being the line of Kings and the other the spiritual caretakers being the line of the family of his brother, Jacob. I also notice that Nephi ensured redundancy in the spiritual care of his people. While he was yet alive and energetic in the active care of his people, and while his people looked to him as both their spiritual guide and their physical protector, Nephi actively consecrated Jacob as a spiritual teacher and made sure that Jacob was active as and seen as a source of spiritual direction for his people. Also before his death, neighbor consecrated Joseph as a spiritual leader among his people so that by the time Nephi passed on the people still has two acknowledged spiritual leaders to guide them.

The Lord has instituted the same kind of redundancy in the modern church by having each apostle ordained with all priesthood keys such that with the death of any number of the members of the First Presidency and Quorum of the Twelve Apostles the senior remaining Apostle has full authority to lead the Quorum (whatever its size) and the action of the members of the Quorum can authorize someone to serve as president of the church and individually exercise all priesthood keys as well as direct anyone else in the exercise of any priesthood keys. To terminate the current organizational authority and require a new restoration of keys (which is not going to happen) would require the functionally simultaneous death of 15 prophets, seers, and revelators. (Good luck with that, Satan.)