What if this is Gortash's way of having a plan to betray the others. Just as Durge is planning to end the world, with himself and Gortash as the last living beings, what if Gortash was planning on "liberating" Durge from their bhaalspawn flesh and blood. Durge would be a part of Enver's perfect order. Maybe both of them are hatching plans to subvert the other for their cause, tyranny and murder respectively. This is a wild rabbit hole indeed.
Let's say, Durge somehow defies daddy Bhaal and Gortash does not bite the grass.
Let's say, despite tireless efforts Bhaal doesn't rly like letting go of his kids, esp not those crafted from his own flesh and blood.
Let's also say, Gortash, the mad unethical scientist, would find 'ways' for Durge to get rid of the burden that is their Bhaalspawn body (essence may be gone but that body still Bhaals property technically).
And now, cuz I'm feeling funny, what if the Steelwatch and the whole consciousness/souls bit Gortash got going on is precisely with that in mind? After all, Gortash is a tyrant obsessed with freedom. And Durge is his equal. So of course he'd assist in their escape from their own hell, too. And if what they need is a new vessel to store their consciousness, well, Gortash and his mechanical puppets are happy to oblige.
I'm onto smth I know it (and this is definitely not just a scrapped ending that I've been reconsidering again)