As far as this stuff lasting, don't make me laugh! Rudy Valee's stuff was supposed to last too! Bing Crosby anyone? Cole Porter, Irwin Berlin are nearly forgotten now considering their prodigious output, and will be completely forgotten in a couple of decades, save for a small handful of embarassing lounge standards and jazz themes. It's a generational thing, that's all. I made a note recently of how the oldies section in my local TOWER Records outlet has been shrinking over the years.
I'm reminded of a quote in a Russian film I saw recently (The Russian Ark:
"Everyone knows the future, but nobody remembers the past!"
Even George Harrison knew that "All Things Must Pass"!
"That's not old enough to be on "Flashback"! It's not an oldie (yet)!"
The truest of all of the curses put upon man ... you will grow up to be a curmudgeon just like your parents!