I am but one of some people who think that the advent of Mr. Marsailis is precisely when "jazz" began to die.
Jim, I think you give too much weight to Mr. Marsalis. I do not consider WM either the "saviour" or the "destroyer" of jazz. At that particular juncture in jazz history, say 20 years after Coltrane's death, and probably 100 years after the misty beginnings of jazz, someone like Marsalis coming along and digging into jazz's history was was probably inevitable. After all, lots of young players were doing it before WM and lots did it after, and lots will continue to do it. The only difference was the WM had a fairly high public profile. But how exactly did the advent of this one man cause jazz to die? He didn't actually STOP anyone from playing or recording or listening to more cutting edge jazz. There was still lots of it out there. You think it was selling lots and getting lots of airplay before WM came along? If jazz began to die, it was the author of its own demise.
Now I'm no great defender of WM, but it seems to me that if you're going to do some cutting edge jazz or "move it forward" (whatever that means), you'd better have a pretty good understanding of its past.
One of the things that gives credibilty for me to a lot of Coltrane's 65-'67 music, and at least causes me to give it a good listen, is that you know this guy was rooted, and man, could he play the blues (one of the greatest blues players in the history of jazz, IMHO). Don't know much about Turner or Rosenwinkel, but from what's I've heard of Chris Potter, I think he's pretty solidly rooted. Joe Lovano, too, who I think is a good model for a creative jazz musician in this time - rooted in what's come before and not afraid to go there, but also not afraid to push the envelope sometimes, either.
You may be right. All I know is the way the "job market" for jazz changed (and it defintely did change) after, say, 1984 or so. And as the nature of the gigs made available changed, so did the nature of the players who were called upon to play them. "Up front" was no longer desirable, "The Tradition" was, no matter how lamely or half-assed it was rendered (of course, the fact that that type of spirit is in direct contradiction to "the tradition" was lost on the participants...). I know from experience that more than a few no-playin' (literally as well as relatively) fools got a "name" in several cities just because they put on a suit and played all-acoustic sets consisting of "jazz standards" (tired jazz standards at that). That became what jazz "was", and that's what got the gigs - image and attitude, not music. You may say that that's always been the case, and you'd be right to an extent, but we're talking about totally closing off outlets that had heretofore been tenuous yet viable. That sort of thing does take its toll, especially over the long haul...
It wasn't Marsalis' music that did it, it was the half-baked (yet fully swallowed) dogma that he so zealously promoted. I've blathered on about this many times in the past, so I'll spare everybody another go 'round. Bottom line though - things changed dramatically, and the chill still lingers, although a thaw definitely seems to be underway, thank god.