I don't think Kellhus found Oblivion, nor was he seeking it. I think Kellhus may well have been saved, possibly by Gilgaol, since only War and Birth can seize apparently (and Kellhus basically did nothing but wage war from the time he left Ishual up to his death). In addition, when he looked up at the Inverse Fire, he did say that he was already saved.
All that being said, I also think there's some difficulty in interpretation regarding the Gods and how humans can become their "vessel". I think it may be erroneous to imagine that possession by a God somehow "overrides" the actual individual being possessed. Rather, I think that being a vessel for a God is the result of someone acting/thinking in a way that aligns with the motivations of the character and the God equally.
Taking Cnaiur for example, who we know to be both a Ciphrang and ultimately a vessel for Ajokli -- his final scene and dialogue make sense regardless of whether you imagine it to be Ajokli or Cnaiur. The same sort of thing applies to Kellhus in the Golden Room, or even Psatma as Yatwer. When Kellhus returns to Momemn and confronts Psatma, he speaks to her and references her as if it were in fact just Yatwer (calling her his sister, the line about how "even eternity can be blind" or whatever). This also plays pretty well with the themes of souls "feeling in control" even then there's a clear puppet master -- be it a worldly one like a Dunyain, or the Cants of Compulsion, or being a Vessel for a God. Kellhus even points this out to Kelmomas in TUC when he mentions how Kelmomas can't distinguish between whether it's himself or Samarmas who is currently speaking/in control.
On a whole separate note, the nature of Ajokli is strange even according to what we know about the Gods. He is at times their adversary and also their companion. He has many, many dominions, including both murder and deception, game-playing, mischief, etc. Not to mention the symbolism of four Horns, Ajokli's claim that the Ark is "his place", the new glossary entry about the Ark being the Halved-Crown of Ajokli, etc...
I do think it's possible that Ajokli is, in fact, the God of Gods, or that Ajokli is Seswatha, or both (the idea of making a pact with the pit and attaining temporal power and so forth fits pretty well with what Seswatha seemingly is/does...but then the same could be said of Shaeonanra and Shauriatas).
Ultimately I think we just don't have enough information to really know yet. I mean look at the list of entities/God-like beings we currently have and who are seemingly all different from each other, while also sharing a number of qualities.
The World
The God of Gods
The Ark
The No-God
The Zero-God
The Meta-God
Ajokli
Seswatha
Shauriatas
That's a long list, and I'd be pretty surprised if there was not some degree of "collapsing" among the above entities, and it's just two or three different forces that are being interpreted differently by the characters, or perhaps are themselves different "stages" of the same force/entity.
If I had to guess, I would say that Shauriatas is the Will of the Ark, and that the Ark simply possesses whoever is at its helm, so to speak. Of course, given the blindness of souls to their own movements as I mentioned above, those possessed by the Ark/Shauriatas do not realize they are possessed.
The God of Gods is apparently blind to the No-God as much as anyone, and given that Ajokli seems to be blind to the No-God as well to some degree, there may be a correlation here.
The World seems to trump everything, and Bakker has described Earwa as a "self-moving world" -- and I also think that this is the sentient entity that is the Judging Eye, or the Zero-God.
The Meta-God, who has only been mentioned a single time, is IMO either a different term for the World, or perhaps a term for Seswatha (and, again, I could see the Meta-God being the World being Seswatha).
Then again, the No-God itself seems to genuinely be the Absolute, given that it stands "outside the outside" and even the God of Gods cannot see it, which would ALSO fit in with the title "Meta-God" (a God that is above the God of Gods).
In conclusion, I have no idea.