Stirling gives us much to think about, as usual.  I don't happen to agree
with him, mainly because his explanation leaves out why we see the same
phenomenon in the other arts.  I doubt the audience for serious literature,
for example, is any larger than that for classical music, and it may well
be less.

One of things I believe is happening is that in a corporate culture,
making a modest profit is no longer a desideratum.  Making profits
comparable to pop successes is the only legitimate goal.  As a result, you
have a scramble to find something that will appeal to broad numbers, very
hard to do with the hard-core classical audience, which tends to divide
into many niches, a lot of them incompatible.  You also see this in book
publishing, now that media conglomerates have essentially taken over most
of them.  I doubt that Faulkner could get published by a company like
Random House today.  So the "real" activity happens outside that culture,
with smaller publishers and labels like Naxos, Chandos, ECM, and Hyperion.
We also see this in the American movie industry, with studios turning out
mostly brain-dead blockbusters and the interesting stuff coming from
smaller independents.

Dare I also mention that the decline of education in the US, public and
private, might also have something to do with this?

To paraphrase Frank Zappa, classical music is not dead; it just smells
funny.

Steve Schwartz