Stannis is not dead
1) he had is sword planted right next to him in the scene very clearly and even crippled he could still take Brienne out
2) before Stannis says to Brienne " Do your Duty " her face changes
3) the sword strike and the noise she made after was very strange, she hit towards the ground and not at Stannis
4) Stannis seemed to have been looking at something in the background moments before the strike
5) Pod took his axe and followed Brienne, maybe Pod slaughtered Brienne in the best twist yet
6) Sansa and Theon might have been behind them running through the forest and thats what Stannis saw, alerting Brienne before she could finish him off
7) Melisandre is clearly going to think Stannis is ****ed and she has got out of it alright, Stannis is the only guy living who knows she deserted him
8) Melisandre said she saw Bolton Banners burning which could yet still be true at the hands of the One True King
9) Salladhor might have been in the forest hunting for boar and stabbed Brienne in the back
10) maybe Thoros is in there as well hiding behind a tree and ready to pop out and resurect Stannis
My King Lives