"We will raise a Black Keep in Baldur's Gate. Then we will conquer the Sword Coast, and unite all its peoples under our rule."

'K, so:

A) That's confirmation that the Banites we encounter do not have a temple as their base of operation, they might have a shrine in one of the temple districts at most, but nothing more. Perhaps private shrines in their own homes, club houses, whatever. I hope the Bhaalists are annoying about the fact that their god got a proper temple: their god was actually important in this city (and if all goes well: will be once again)

B) "We" are going to raise a temple of Bane and rule as his iron black fist are we? Even if we're the Chosen of Bhaal? I think he might have issues with this. Then again, Bane is under the full belief that Bhaal and Myrkul are his lackeys and will fall into line... On the one hand with "redeemed" Durge, the idea that Gortash hears "father disowned me" and basically just smoothly moves onto converting them to Banite without actually explaining it or consulting them is fucking funny.