changing of the guard

noun2

1. •
   A ceremony during which the soldiers or other officials guarding a major government building or state residence, especially Buckingham Palace in England, are replaced by a new shift.
2. •
   (figurative) Any situation in which an individual or group charged with a task or responsibilities in an organization is replaced by another individual or group.

   • All the signs are right this time / You don't have to try so very hard / If you live in this world / You're feelin' the change of the guard — 1972