Here's a guy, Michael J. West, who thinks it isn't and sets out the reasons he thinks that. I'm happy to go along with them. I read the article by Benjamin Schwarz that West takes issue with, and found it, as he does, too narrowly focused. But one thing I would add to what West says is this: even if it were true that the jazz idiom was no longer producing vibrant music, no longer coming up with the goods, developing them, those of us who love the music would still have what we have from all those decades. I mean, no one thinks that Bach is dead, or Beethoven, or Mozart or Schubert. So, if jazz stops altogether in its tracks tomorrow (which it won't), we'll only have Armstrong and Bechet and Goodman and Ellington and Beiderbecke; and we'll have to make do with Monk and Coltrane and Miles Davis and Bill Evans and Gerry Mulligan, and a list I could make as long as both my arms. It ain't dead.
One other thing I'll say, though. When I first got into jazz in the late 1950s, jazz was cool, capital C. It still is, of course. But back then it was perceived as cool. Now, sometimes, if you confess to loving jazz, you can appear in some company as an old relic. This is very bad. I blame the follies of the world. (Thanks: DA.)