Some are now getting old enough that it is an issue.
I remember seeing Joan Baez a few times in the eighties, not because she
was getting old but because I wasn't sure if she'd come to town again, and
after 3 or 4 visits, she didn't until a couple of years ago.
I was sort of thinking of going to see Odetta when she came to town in
early 2009, but that show was cancelled, either because she died or
because she was ill (the illness did lead to her death). I saw her at
least once in a really small venue in the early eighties, but I would
have liked to see her again.
Each year they get older, seemingly out of the period when they were young
and died of drug overdoses or other things that young people die from, and
the next time they come to town could be the last.
It's too late after they are gone to see them again, or to say "thank
you".
Michael