User blog comment:Xilinoc/Ch. 609 - "A"/@comment-5693502-20141211131448/@comment-24913480-20141211142555

That's like saying: "we'll just leave the hard work for future generations. I'm sure they won't mind watching their friends die at the hands of this bad boy because we just couldn't end him ourselves. Procrastination rules!"

No, Yhwach was already sealed once a 1000 years ago, after his fight with Yamamoto (we don't know how or by whom but it happened). He has to either be truly defeated or pull a "Nagato" (Naruto manga - turn good guy at the last minute) although that would be anticlimatic. Getting sealed yet again would feel like a cheap move from Kubo.