These are all very perceptive and accurate comments. There's just one drawback to the application of the term, however--it tends to focus on the big hits. "Sunny Afternoon" by the Kinks is certainly classic rock, but "Fancy" from the same album is rarely heard today, even though it's at least as interesting and innovative. Certain entire albums have proved timeless, though they weren't particular popular at the time ("Village Green Preservation Society" to stick with the Kinks, or the first four Velvet Underground albums).

Still, as you suggest here, the term is a very important barometer for measuring today's music, much of which though immensely popular right now isn't likely to stand the test of time as classic rock has.

Keep on truckin'.