I think the whole Sabo (and Vivi) captured thing is to build up a Marijoa/rescue arc. We have also Coby bringing Boa, plus there is stuff like Green bull, SSG but also Dragon (and maybe Weevil) who need to appear asap on panel and then Kuma and Bonney too (to respect how in each in the new world so far we had at least a supernova show up somewhat). Also this recalls a lot what Oda was doing with the Ace adventure pre time skip. All the points will be linked in this arc. And imo it will be the next (Sabo and co need to be saved now), maybe Elbaf comes after this one.