I think there's quite a few that have gone on too long...
But some have gone on 30+ years..Cliff Richard's later CD's are much better than a lot of his earlier ones..Some of that is because of the quality of the lyrics..
I realise he is more UK popular of course.
The Rolling Stones still rock...
I think The Who have done good, even though they lost half of them along the way...
Many had early deaths as well....
Not being really ageism..after all I am 72 myself....but look about 18 years old now...haha