Where is the Sanji option? Would be ironic in the sense that Sanji wanted Zoro to kill him/stop him if he becomes evil however Sanji is the one who will save Zoro now, time for Sanji to settle the Thriller Bark score in some way. Don't get worked up about this suggestion it is just one of the many possibilities. The Zoro panels clearly indicate that his role and plotline is far from over in this arc I think.
Are we sure that Zoro is indeed falling off Onigashima, he must be saved cause he is not surviving falling from that distance, there might be more bedrock so he falls to a lower level of the island instead of all the way down to Wano. What are possibilities here, I mean Franky was already looking for him, Sanji hid a transponder snail so that they could find Zoro if he were to face death in some corner, so Franky can maybe locate him. Yamato has not met Zoro yet and she can be fast with her mythical beast so she might be able to save him and then we can get some flashback or backstory with the Ushimaru thing. Marco has been missing so he might actually help Zoro again, the guy is carrying him on his wings, first he sent Zoro to rooftop then saved him from King's attack and now he might save him again. Momo might be able to save Zoro with the clouds but I think it would be pretty difficult for him and if he goes to save Zoro and he might let Onigashima get back over Flower Capital.
Denjiro has no ability to save Zoro so I think we can rule him out as well as Tenguyama since he is in Flower Capital and Onigashima is now at a distance from it.
Zoro has also either fallen face first or rolled over since he was facing the Death Reaper with his back on the ground but now we see him lying face down, what happened, I hope we get to know it soon.
Btw holy shit that single bomb destroyed so much of Onigashima and BM got nuked the next time (the bomb that is falling with her looks like a missile or nuclear bomb thing). On first read I thought all the bombs that Yamato froze fell with BM and one exploded on Onigashima and the rest in the hole but the other frozen ones are still there with Yamato. And then you see that there is this nuke that is falling with BM into the hole. So to defeat a Yonko you need to deal shit tons of damage and then nuke them afterwards. I seriously don't expect Luffy to defeat Kaido solo after what we saw BM tank because Kaido is supposed to be even tankier.