User blog comment:Xilinoc/Ch. 682 - The Two Sided World End/@comment-26091912-20160713132058/@comment-1970092-20160713210215

It makes sense. Old Man Zangetsu has the appearance of Yhwach from 1000 years ago. Look back at chapter 541, when he gives Ichigo the sword covered in flames, it has the same shape as Yhwach's sword.

I think it's far from Kubo being out of ideas~