I would have thought that three-quarters of the Folk songs written since 1970 are about the end of an era .... Personally, I always liked John Hartford's The Goodle Days:

Some day about twenty-five years from now,
When we've all grown old from a-wonderin' how,
We'll all sit down at the city dump,
And talk about the goodle days.
I'll pass a joint, and you'll pass some wine,
And anything good from down the line;
A lot of good things went down one time,
Back in the goodle days.

Something like that, anyway.