The Dalai Lama retired from politics last year at the age of 75.
As a reference point, I still have 15 years to go before reaching that venerable age. I can quit worrying about what to do and when to do it I guess. For now.
If the last Buddha (approx. 500 BC) was number 4 and the potential is for 1,000… well, human beings still have a long time to work on their evolution. The Buddha is said to have been every kind of living being, every animal, every sort of human before he attained enlightenment. Eons of existence and rebirth.
Buddhists believe that the universe is infinite.
Coming to the realization of infinity and eons really makes the subject of retirement a non sequitur (irrelevant, curious and perhaps humorous).