Age 40 is the absolute limit. The Beatles were all 30 or less when they ended. Then 10 years to have some "me time". Yes there were other projects for those still alive, but I think 40 is a good limit. I proclaim that we should all boycott live performance and new albums of anyone older. I have spoken.
The Beatles did not tour with their psychic stuff at all. I have a hard time accepting this as the "right time." Guessing about "what other albums would have come out" neglects the other half of this cranium which is live music.