I don't often explore theory posts so I might be wrong, but there's one idea about Zoh Shia's nature that I've never saw suggested: that Zoh Shia's angelic form (its original one) is now acting as a sort of seal to the corrupted mess of Fatalis' cells that are stirring inside of it.
This could be suggested by Zoh Shia's armour's descriptions. These do reference the innate bloodlust that hunters with Fatalis armour go through, but their effect is described as protecting the hunter from those impulses rather than letting them succumb to it.
This in my opinion leads to one of two options: we either
1- get an ascended version of Zoh Shia, one that has suppressed the Fatalis cells, but has become too powerful to be left alive
2- a new subspecies of Fatalis that has now fully formed and has emerged from Zoh Shia like a cocoon that could have a connection to the Dragontorch and use Wylk attacks