Many are rightfully assuming that with Saint Jay Garcia Saturn arriving, he will command the Seraphim to go against the Strawhats and Vegapunk. It has been said multiple times that the elders have ultimate control, so that’s also a possibility.
What has also been emphasized in this arc is both Bonney’s Devil Fruit abilities and how the Seraphim are in their infancy. In Chapter 1072, Bonney tells Vegapunk her abilities are only temporary.
Bonney’s entire drive right now is to find out what happened to her dad and why. She also attacked Luffy when he went to attack the Pacifista, purely off emotion.
Assuming Bonney is still on the island (since Vegapunk mysteriously disappeared), I believe that once Saint Jay arrives, he will inform Bonney that Kuma is currently attacking Mariejois and that he will spare his life IF Bonney uses her abilities to temporarily age up the Seraphim.
That way, he takes full control of the matured Seraphim, giving the strawhats as much trouble as they had against the Pacifistas in Sabaody. This temporary age up will give the audience a glimpse of their full power for the final war.
Bonney will do it because she wants to protect her dad, and if/when she sees her dad’s memories, she may be in an emotional wreck and absolutely determined to protect his life, ultimately betraying the Strawhats.
I believe there will be another arc mirror of Luffy punching a Celestial Dragon with him punching Saint Jay (this is also another common theory people have been speculating). I think Luffy will do this to try to stop the Seraphim on top of just being angry that Saint Jay is using Bonney’s emotions against her.
So the Strawhats, Stussy, and the Vegapunk satellites will be up against the matured Seraphim, Kizaru, potentially Lucci and Kaku if they’re freed, and however many other marines. Let’s see how far they’ve come.
Theory by brickheadjones (https://www.reddit.com/user/brickheadjones)