"...the median age of NPR’s radio audience has steadily climbed from roughly 45 years old two decades ago to 54 last year—and one it would need to reach in order to guarantee its survival."
I've been in nonprofits since 1993. My wife has been in different nonprofits since 1998. My friends are mostly in nonprofits. Every single one I'm aware of--with the possible exception of NYPL--has dealt/is dealing with an aging constituent base. Every interview I go on, they want to know what I can do to help them reach, court, and convert young people.
Not to diminish NPR's problem ... that's a pretty fast aging rate compared to some others I've seen. But clearly there is something going on here that's bigger than NPR.