Had Shin avenged Gaku Rai and slain Jyou Ka Ryuu, we could've had an interesting reveal of Shi Ba Shou.
Just picture Gaku Shou and Fuu On returning to Seika, reporting to their lord what had happened as he stood over JKR's body.
We could've gotten a bit of dialogue before face reveal, in which SBS remarked on how JKR had been a loyal vassal and friend to his late father and the one who trained him in arms as a youth. Shi Ba Shou would then vow to avenge his death and ask of Gaku Shou who was the one to slay him.
That could've been a cool moment for the face reveal as he turned and repeated Shin's name, vowing again to avenge JKR.
And just like that we'd have a more personal storyline involving the Seika generals in the conquest of Zhao.
(And in the end, perhaps Shi Ba Shou would leave Seika's care to Shin, after deeming him an honourable man and worthy adversary to whom he could entrust he city his father had entrusted to him, but that may be a bridge too far.)