My wife and I attend more classical music concerts than most - 60-80 a year, mostly in the SF Bay Area and about 25% in our annual sojourn to London. In general, being in our late '60's we are among the younger half to third in most all audiences. The only fortunate demographic is that people are living longer and seem to be healthier. Not sure about their hearing however. We see more people in wheelchairs and using walkers and other mobility devices among the audiences. The London audiences are a bit younger, but not much. They do seem to have a fair fraction who are in their twenties and thirties, while the younger people in the SF area concerts are often children and teens (frequently of Asian parents) who are brought to the concerts by their parents (often mothers).
The point of music programs being eliminated from public schools may be significant cause of the lack of interest from young people. In the past couple of years the two concerts I remember most for having a large number of young people was one with clarinetist Martin Frost (wearing rather tight leather pants) and other with percussionist Colin Currie who dazzled the audience playing with the Philharmonia and nine different instruments (both concerts in London). I didn't notice whether there was a younger than usual audience at a recital of pianist Yuja Wang, where she wore one of her micro mini skirts and sky high heels.
One important trend to attract a wider audience are the simulcasts and rebroadcasts of opera at local movie theaters. Both the Met (which is doing the most) and the Royal Opera are doing this and there may be others.
Certainly opera, ballet and orchestral concerts at the highest level are generally not for the poor. There are cheap seats, but not too many. Also most all of the performances are heavily subsidized by contributors (and the government in the case of London). It reminds me of the era before the 19th century when the wealthy in Europe had their own orchestras - essentially the government subsidizing music. This is also true of the fine arts - where the great art collections of the world were almost all created by the very wealthy and now reside in places subsidized by the governments or wealthy individuals.
An interesting phenomenon in Asia is occurring with the sponsorship of orchestras by corporations. The one that attracted my attention is the Malaysian Philharmonic, based in Kuala Lumpur. It is basically the orchestra of the Petronas Oil Company. They have imported a large number of their players from overseas, mainly Europe, as well as their conductors. They have several recordings on BIS. However, there are dangers with changes in the economy or management and this is happening to them right now. BTW, this was true in the old days, when a wealthy patron to a composer would die and be succeeded by a tone-deaf relative - happened to Bach among others.
Finally, recordings of classical music are suffering from the same problems with the skyrocketing costs of large productions. There are essentially no studio recordings of operas (those released are of live performances either staged or concert performances) and many of the orchestral recordings are of either regional orchestras, usually non-US based, or major orchestras who record on their own labels - again mostly at live performances, where the musicians are not paid extra, except for potential royalties.
Larry