[God luvs America]

Could be but all I know is when I listen to "progressive rock" stations in New York Zeppelin is the only group they play the whose band members were born prior to 1970

[general_re]

Right, and I think that, given how they've obviously and directly influenced two generations of musicians, their place in musical history is secure. But it's a stretch to say that in 50 years you'll be able to flip on top radio station in town and hear "Black Dog" or "Stairway to Heaven" - if for no other reason than because every generation wants something that belongs only to them, and not to their parents. Muddy Waters was hugely influential too, but he doesn't get much airplay outside of the niche stations these days ;)