As to rap becoming folk material, first I have to confess I don't like far-and-away most of it that I've heard. Just so you know my bias.

That having been said up front, it seems to me that rap is not likely to be learned by the listeners and done by them and passed along. I see it as a performer "art" only. Perhaps there might survive a tradition of off-the-top-of-your-head rap, like off-the-top-of- your-head calypso, but the individual pieces being handed down? Nah.

YMMV.

Dave Oesterreich