FWIW - I have seen several symphonic shows this last year, and will see a few more - they happen to be local orchestras accompanying Beck or The Blackstar Symphony (including musicians who played on David Bowie's final album). Beck's catalog is filled with incredible orchestral arrangements written by his father, David Campbell, it's great to finally hear them live. Trey Anastasio from Phish is also a "serious" composer who writes for orchestra and varied ensembles. I think this is a viable way forward for orchestras to at least fill their calendars and attract people who might not have come to see a Mahler or Beethoven symphony.