I HOPE you are correct on all points. But I just can't see Brianne letting Stannis live.
All that Build-Up of Avenging "Da Renlys", I can't see her finding it in her heart to let him go.
>>All that Build-Up of Avenging “Da Renlys”, I can’t see her finding it in her heart to let him go.<<
I thought that too, but then thought more on his line - “Go on. Do your duty.” Might have struck her that her duty to protect Sansa is greater than her desire for vengeance. Perhaps it changed her mind, and she just struck the tree above his head (another off-screen “death” cliffhanger). She’s not a murderer. I can see her bringing a wounded Stannis to Winterfell as an exchange for Sansa or something along those lines.