So I saw a "Great Courses" ad for their "30 Greatest Orchestral Works" and was a bit discomfited to realize that there was nothing more recent than 1953 on the list. It starts in the 1720's with Vivaldi and Bach, but ends in the 1953 with Shostakovich's Symphony No. 10. (And a sad lack of Sibelius...) So, 230 years of orchestral works == about one "greatest" every eight years.
Is it plausible that we have gone 60 years without any great orchestral music?
Possible, certainly. A nearly equal span of time passed between the Bach and Mozart pieces Dr Greenberg chose. And the rise of all the strains of popular music has certainly diverted some energy and talent from the orchestral tradition.
But no movie composers? No postwar modernists? None of the Jazz musicians who have tried their hand? I would think it shocking for any great literature survey to cut off the last 60 years of work by ending with "Invisible Man" or "The Old Man and the Sea."
I can't decide whether this is a deliberate critical choice, a preference for honoring dead composers over live ones, or just a failure to engage.