Let's see here, The 9 or 8 divines are only in Empire, Dominion, neutral, or stormcloak controlled provinces. And since the Tsaesci and the Kamal are from Akavir ( Which the Septim Empire tried to take over but failed to) I don't think they believe in the divines. Besides, the Kamal are literally frozen in ice and the Tsaesci ate all the men in Akavir. ( Also killed an emperor during the Septims reign ) I don't think any of them would be converted. And for the Maormer, they hate the Altmer. And they've been isolated from the other provinces for I don't know how long! And I don't think they would side with anyone who are with the Altmer or share their religious beliefs. Anyway, that's my belief.
For Yokudan mythology, look to the Reguards. It can be argued that they are both the same and also not the same as the Eight.
The Maormer are strictly Lorkhanic/Padomaic Mer. Their king was made from the skin of the Serpent, who is Lorkhan.
Well, here there's Tosh-Raka, who is an obvious subgradiant of the Time Dragon, a part of Aka. Given this, it seems possible there are other potential Divines, but we have no information about it at all.
Keep in mind that the concept of the Eight Divines is something very old. Both ancient Atmoran and ancient Aldmeri pantheons contained the Eight. It was because of this that the Alessian Order were able to integrate the two religions together to form the Cyrodilic pantheon so well. There's obvious holes and gaps in the Alessian Eight, but it made enough people happy. There are also the Eight Divines as in "heavenly bodies," i.e. the Plane(t)s. It's quite obvious that the Eight are fundamental to the mythic structure of the Aurbis (eight spokes of the Wheel).
Talos' plane(t) is Nirn/Mundus which is unclaimed by any specific Aedra and was seeded by Lorkhan's death. Due to Talos' rise to godhood he assumes Lorkhan's position in the pantheon if dev forum posts are to be taken as canon.
Furthermore, considering we literally use a divine power provided to us, the player character in Oblivion to put an end to Umaril. We as an outside observer to the universe know Talos to be a true deity because we have interacted with him where he acts in his capacity as a deity assisting the other divines.
I guess this is how I manage to get people to respond: say unequivically something controvesial. I rarely get responses to my polite and thoughtful posts. Ha, ha.
In any case, good point. I gave you thumb! :D
My point was more along the lines that to be a Divine specifically, rather than any sort of god, one has to have a planet to claim, which is what sets them apart from just being "Aedra", even powerful Aedra like Trinimac, Jephre, Auriel who ascended, etc.. As for Nirn being Lorkhan's planet, according to The Lunar Lorkhan, Lorkhan already had his own planet, which was the one the moons were made from (including, if the Khajiit are to be believed, the mysterious third/dark moon). Arkay was also said to be a mortal once, just like Tiber Septim, and yet Arkay has his own planet that isn't Nirn. Nirn seems to me to be neutral ground; if anyone can lay claim to the planet Nirn, it's Nirni, the spirit of Nirn, who the Khajiit claim is a separate Et'Ada. As far as I'm concerned, at least in the technical sense, Talos isn't a Divine, even if he is a god (maybe even a more powerful god than the Divines).
There's also the matter of jungle still existing in Cyrodiil in the late third era (a.k.a. Elder Scrolls III: Morrowind). I'm open to the idea of Talos being a god, but even the Arcturian Heresy can't explain away why the jungle was still there even after the Warp in the West. It sounds very much like clearing Cyrodiil's jungles was just attributed to Talos retroactively because nobody really knew why it happened, i.e. it's pro-Talos propaganda. I'd like to believe Talos is who he says he is, but it could very well be that someone or something else is posing as him and that Tiber Septim never achieved apotheosis.
Edit: To address why Tiber Septim's blood was able to qualify as being "the blood of a Divine", Talos was a Dragonborn, which means he had the blood/fragment of Akatosh running through his veins. It's no wonder then that Martin Septim was able to materialize as Akatosh given his avatar's own blood was used in the ritual.