From a writing perspective, the obvious thematical follow-through and conclusion to Kan Ki's arc, which is presently in what you might consider its "fall phase", is comeuppance in the form of terrible consequences for past misdeeds. That is to say, at his end, Kan Ki begets what he has inflicted upon everyone he's come across: pain.
In other words, Kan Ki being tortured to death is what seems like the most obvious if not most conventional route for Hara to go.
Perhaps he subverts those expectations. Perhaps not.
It's entirely possible Hara's twist end to Kan Ki will come in the form of Rin Gyoku suddenly - and to everyone's collective shock - decapitating Kan Ki to spare him an ugly end, taking his leader's life in a most grotesque and final expression of loyalty and love. (If that did happen, I imagine Fu Tei would then quickly end Rin Gyoku's life as a final courtesy).
It could be something else entirely. Whatever it is, I'm very curious to see how Hara is going to kill off the first Six Great General since Ou Ki, i.e. since practically the beginning of the manga. I am reminded of how much I posted this arc was similar to Bayou. That may come full circle.