User blog comment:Kaido King of the Beasts/Chapter 813: Up in Vinsmoke/@comment-5398287-20160121132556/@comment-2125188-20160121154733

But Jack only left Zou cause he heard what happened to Doffy. And for all we know he may still think Raizo is on Zou, and will stop at nothing to find him. I don't think Jack's the sort of guy who will just leave never to return again without getting what he wants. It's only logical to think he will return to Zou. Of course there isn't going to be 100% solid proof that he's coming back, but the way the arc is headed and the reasons i mentioned makes it seem more likely than not that he's coming. And just because he comes back it doesn't mean the straw hats are gonna beat him (fyi, do think Luffy is on Jack's level, but let's save that debate for another day)

Even if Jack doesn't come back, a enemy will come to Zou (whether it'd be Weeble, someone else from Kaido's side to finish what Jack started, or someone else who was affected from Doffy's defeat who is looking for Luffy).

And what do you mean Luffy and Zoro's apathy to Sanji's note? Those 2 didn't even appear this chapter. And didn't Luffy wanna save Sanji as soon as he heard he was in trouble a few chapters ago (correct me if im wrong).

If you think this arc is just transitional and they're not gonna rescue Sanji straight away than where are they gonna go? Are they just gonna sit on Zou twiddling their thumbs? Will some of the crew just sail to a random island while the others tie up the loose ends on Zou?

Let me tell you something: whether it'd be saving Sanji or tying up loose ends on Zou (which will have major events), one of these things (or most likely both) will happen straight away.

Also, I don't want the crew splitting up again either. No one does. But with loose ends needing to be tied up on Zou, and needing to rescue Sanji they will split up again. It would be pointless to have the entire crew tie up loose ends on Zou for the next 10 or so chapters (will be at least 20 in my opinion given the Raizo stuff) while the Sanji stuff (which is the meat of the arc right now) is put on hold.