To me, the Alliance being there is largely irrelevant. What matters is how much of Saurfang's actions come from himself and what his motives are. If Saurfang's motives are provided by the Alliance, that's what it'd take to ruin him for me. I don't see that happening here. I feel he's going to reexamine his priorities on his own for now, maybe with one last important figure to talk to before he settles on his outlook and plan.
Anduin himself has never been what Saurfang was afraid of. He was worried about the non-Anduin influence in the Alliance, or who Anduin might be later. Not the Anduin of now. To anyone with eyes, Anduin is a liability to the Alliance. He's holding them back. He muzzles the dog. He tries to talk peace when he should be waging war.
Looking at Anduin from Saurfang's perspective, now in that cell, I'd be seeing someone who refuses to win. I wouldn't be worried about what Anduin wants or is doing. I'd be worried about how long Anduin is going to be allowed to continue his self-sabotage before someone shoves him the fuck out of the way. What Anduin wants isn't the important factor.
And that's where I think the Alliance story is actually headed. Tyrande and Malfurion won't stand down. Even if Sylvanas is pushed out quite soon, any attempt by Anduin to stop the war is probably going to get some loud voices telling him to fuck off. The Void Elves and Alleria are going to push for Silvermoon, Tyrande will demand Saurfang's head, and Genn isn't necessarily going to take Anduin's side.