Sometimes what happens is that something doesn't exactly survive as a distinct form, but exerts its influence on other established forms, and lives on through them. Rap is doing this now to rock and roll, and may similarly end up influencing other musics before it has run its course; we may end up with some of the flavor of rap surviving even after the form itself has disappeared. In fact, if you listen to Ani DiFranco, you'll hear some of it now (and while Ani is not a traditional folkie either, her demographic overlaps with more traditional strains, and might end up influencing them). I'm not really a rap fan either, but there might be something in the rapid-spoken-word, rhyming-couplet thing that has value.