I think your theory is definitely in the right vein.
I have a hunch that this is going to lead to some Zarosian Civil war, Now that Azzanadra has ascended, and whilst he insists his loyalty, even a former loyalist such as myself can see the exact same process that occurred in me, happening to him, questioning whether Zaros is truly fit for purpose.
I believe Zaros will likely ascend to become a 'Shadow Elder God' as you propose, and that he may potentially become a primary villain during the Elder God Wars.
It'll Likely Be Zaros, Nex and Zarosian loyalists, vs Azzanadra, begrudgingly, and Zarosian Separatists (I call them this because, assuming i'm right, they don't have a name yet).
It's worth noting that, if we take the parallel between the Zarosian Empire, and Rome literally, this could be a counterpart to the real Life Split of the Roman Empire, granted, the Zarosian empire isn't much of an empire anymore, but you get what I mean.
I also agree about Xau-Tak, from what we just learnt in CoS, Shadow magic is rooted in Shadow Anima, loosely at least, which seems to be the same root source of Xau-Tak's abilities, so, if Zaros pops up as a huge vessel of Shadow Anima, it'll no doubt alert Xau-Tak and his forces.
At the very least, we can assume Jas, Wen, Bik and Ful aren't the only foes on the playing field.
23-Jun-2021 14:18:20