Even in this new age of decentralized hip-hop, I think there are still plenty of rappers that could be considered “underground.” I understand you’re argument that now it’s just rappers, but I’d like to put it out there that the underground still exists. It’s not necessarily about coming out of nowhere, though that can still happen, it’s sometimes more about what it’s not, rather than what it is. It’s not having “mainstream” success, ala Chance and his relationships with major brands, selling out big shows, and being talked about in big publications, not just blogs. It’s not about living off your music, but about sometimes still having a day job. It’s not about Versace, but about fatigues.
Now that I think about it, though, that’s just your thesis restated. You have the big names, with their own lanes, and everyone else.
Some of my favorite underground hip-hop from the last 15 years:
Sollilaquists of Sound