First of all, on the chapter 937 color spread we can see Zoro wearing a t-shirt with a sun as well as the label “Pirate” on its back.
This is obviously a reference to the Sun Pirates where Jinbei and his fishmen fellows once belonged to. The second hint in the picture is the number 972 next to Nami. Putting these two hints together, we could conclude that in chapter 972, something related to the Sun Pirates will happen.
This assumption is enhanced after the plot in chapter 959, where Luffy starts thinking about Jinbe, while he is looking at the sea. Oda did not put this scene without purpose. The reader should see, that Luffy did not forget about Jinbe and hopes to see him soon. Thus, it is indicated that in the near future, we will get further information on Jinbe.
The current chapters deal with the Oden’s flashback.
When the flashback ends, chapter 972 won’t be so far anymore and considering the apparently bad situation where the alliance is at the moment, it would be a perfect and somehow classical Jinbe moment to appear out of nowhere and rescue/help the Straw Hats as he always did. In addition to that, the final war begins and the alliance needs as much power as possible.
Bringing Jinbe back into the current story would therefore be a perfect way to increase the chance of beating Kaido (the chance would still be very low, though).
*Theory by giochecker
