Nieman Lab has done a study of public radio listening habits and discovered that more and more NPR fans are turning to podcasts and less and less of them are choosing streaming.
I think this is not a surprising trend. NPR listeners have really been on the vanguard of podcast listening for years now, and I think the main reason for that is the type of shows NPR airs. Each show is a content island; a short thematic program in bite-sized pieces.
I think this is probably the future of talk radio. Something just the right length for walking the dog or taking a short jog.