See, I think the descent into full Saul is a ways off yet. His brother is the least of his obstacles on that path, Kim is far more problematic. This win over his brother is the first time Jimmy has really turned on his brother and I don't think he enjoyed doing it. My guess is, deep down, he still wants what he's always wanted: his brother's respect. I don't think we're done having that knife to the heart twisted on Jimmy. But the descent into Saul doesn't really kick off until he has to alienate Kim. At least IMO.