As I write this, I'm listening to Jefferson Airplane's song "3/5 Of A Mile In 10 Seconds", off their hit 1967 record Surrealistic Pillow. In quality I'd consider it to be at least the equal of any Mozart piece I've heard, and very nearly rivals my beloved Wagner in quality:
The record was released forty-six years ago - nigh-on a half-century. Now, from my reading, most pop-sociologists peg a generation as being about twenty years long: from the time it takes a person to be born until that person begins popping out the newest members of the next generation. By that reckoning, it's been right at two and one-fourth generations since it was released. In comparison, forty-six years before the release of Surrealistic Pillow, big band music was in bloom and jazz was the hottest thing on the block.
Now, I don't think anyone would dispute big band and jazz are 'traditional', at least in the brief American context. Is Surrealistic Pillow also then 'traditional', a part of Western civilization which Must Be Defended At All Costs? If not, how long does it take for any work to become 'traditional'?