I listen sometimes. I have a bunch of decks that were still worth some money five years ago, but no one wants them today. I should have sold them back then, but instead I was "into" cassettes, and buying. Not bad decks, either; mostly studio stuff. Some of the wholesalers won't even take them any more, or they'll give you a token $2.50 for them if you're lucky, because demand for them, even in third-world countries, is diminishing.
The exception is the higher-end Nakamichis, which people will still buy. Unfortunately (or fortunately, for me!

), my ZX-9 and even my ZX-7 aren't going anywhere (although the 700 and 1000 tri-tracers will be moving along at some point); those are the best-sounding and most flexible ones that I, too, would like to keep.
Cassettes are still listened to by a hard-core group of tapeheads, some of whom you'll find right here on AK, but it's an ever-shrinking niche group of diehards, I think. A bit more common than DAT or DCC lovers, perhaps on a par with Laserdisc aficionados. It's an almost extinct format among the general population, though. Boombox fans still listen to tapes, too, but they're another tiny niche group.