I was recently talking to a teacher from my school who had worked in Saudi Arabia for a couple of years. He is muslim, and I asked him about the ban on non muslims entering Mecca. He told me that he'd had this same conversation with someone he knew in Saudi, and that this bloke had told him that "there are still Arab polytheists in Mecca". He said the conversation was in English not Arabic (removing the possibility of the word "kuffar" or "mushrik" being used perjoratively) and that this man was specifically referring to the pre Islamic pagan religion. He said the conversation moved on from there.
He also said there was a rumour that the house of one of the false prophets who came after Mohammed was preserved in perfect condition in Riyadh by his descendants.
So, reddit, is there any evidence for persistence of Arab pagan cults in Mecca (or anywhere else), in the sense of active worship (not simply praying to face the Ka'aba, fasting or circumnambulation).
Almost certainly not. It's possible that he was referring to the Shi'a. Hard core Wahhabis consider the Shi'a heretics and occasionally polytheists for their reverence of Ali (and, to be perfectly honest, a lot of Sunnis don't understand what the Shi'a believe -- I had someone in Egypt tell me that the Shi'a worship Ali instead of Muhammad ... right in front of an Iranian colleague, who was nice enough not to explode on the scene). The Wahhabi movement started on the idea that there was too much innovation (the word in Arabic is bida')--basically the things that were decided to be religiously acceptable after Muhammad's life--and that the Muslims of the Arabian peninsula had started backsliding -- I was told that they were "worshipping trees" (I've never seen any evidence of this, myself). Again, since the Wahhabi mission was to wipe this out, it seems very very unlikely that there are still pagans and--especially--they could practice openly in Mecca.
There is very little left in Riyadh from the pre-Saudi era (pre-1900) at all -- about one city block, at this point -- so it sounds like one of those urban rumors. And the entire district has been so sanitized by the Saudi authorities to reflect their version of history (see Rosie Bsheer's Archive Wars) that the idea that something that old--especially from one of Muhammad's rivals--still survives is practically impossible. The Saudis got rid of the tombs of Muhammad's wives and children in Medina (and they wanted to demolish his tomb, as well, but there was enough of an international outcry that they stopped) ... what are the chances they let the tombs of one of Muhammad's rivals survive?