A counterpoint. You're describing the American situation. Most (central?) European orchestras are at least partially publicly funded and therefore relatively stable. As they do not rely solely on donation (by old farts as you imply), they are able to experiment far more and also provide a stage for new composers, new works. Same for opera houses. As they are modernizing the interpretations of symphonies and especially the screenplay in operas, they become politically and socially relevant again. There is little worse than enduring a ballet in the style of the 19th century, but watching a modern piece can be a really great experience.

So government endowments enable orchestras to experiment and hence stay relevant. Without those your analysis is spot on.