"rap, punk and reggae have become folk music now that time has passed?"

What does 'becoming folk music' mean in practice? If punk had 'become folk music', how would anyone know? What would that look like?

The genres you mention don't, in the main, lend themmselves to communal, spontaneous, non-professionalised expression. Certainly none of them have become folk music in the sense of there being identifiable songs - standard repertoire - that everyone would know well enough to sing at a singaround.

With one notable exception - Bob Marley. Having been at a festival recently with a lot of late-night round-the-campfire singing, it was noteable how often Bob Marley songs got trotted out and got people singing along. Perhaps 2nd only to Beatles and Ed Sheeran songs.

No punk and no rap. Very hard for rap to ever become 'folk music' in a meaningful sense for the de facto reason that there's a hell of a lot of words, and no singing as such, so very hard for people to join in. I love hip-hop and could probably rap some verses from certain Public Enemy, Gang Starr and Wu Tang Clan songs if I really wanted to embarass myself. But I'd be on my own.

Maybe I'll start a hip-hop singaround for white middle aged men. Now that would be a truly horrendous thing.