NPR stations are typically great content providers, especially for baby boomers and the 35+ crowd, but these stations face the same problems that plague commercial radio stations. The local NPR stations seem to be working feverishly to plan ahead and develope new programming. But for the most part, their content does not appeal to listeners under 35 and for all intents and purposes, it's FREE.
For a generation brought up on free file sharing, free music and free content derived from a hundred thousand websites, the question for NPR and Public Radio remains, "how do we monetize this?"
These are very valid concerns, ones for which NPR doesn't have a firm answer yet. At least not that I'm aware of. Although I'd argue that the free model of public radio has dovetailed much better into the "free content" mindset of the web generation than most commercial content models like CD and DVD sales.
But one ace in the hole that NPR has, and has always had, is that society doesn't change as much as you might think. To put it another way, NPR's never needed to reach out to the under-35 crowd because that crowd has consistently sought out NPR as they get older. After all, the rebellious twenty-something punk with an earring and an iPod today is the balding, mortgage-holding, two-kids-and-a-dog parent with an IRA in when they get to be thirty- or forty-something. When your lifestyle changes like that, it tends to change you in ways that drive you to like NPR.
Personally, I'm not TOO worried about attracting the youth market. I'm MORE worried about how radio relies so heavily on in-car listening because portable internet hasn't made too much inroads there. Eventually that's going to change; it already has to some degree thanks to the iPod and iPhone, but it could change a lot more.