WARNING: The following contains spoilers for One Piece Chapter #1027, "Danger Beyond Imagining," by Eiichiro Oda, Stephen Paul and Vanessa Satone, available in English via Manga Plus and Viz Media.
One of the coolest things about One Piece's Onigashima Raid is that nearly from the start of this arc, our merry band of pirates, samurai and rebels has been faced with a doomsday clock in the background. Thanks to Kaido's flame clouds, the entire island was lifted into the sky and has been on a course straight to the Flower Capital, where the citizens have been enjoying the fire festival. The entire time our crew has been fighting, the threat of Onigashima crashing into the ground below has (ironically) been looming overhead. Now, with chapter #1027, that threat is addressed by Momonosuke and Yamato.
As we return to the rooftop, Luffy addresses Yamato, saying he'll take care of Kaido and that he should focus his efforts on protecting Momonosuke. Although he managed to amass some courage last chapter, the massive pink dragon is still struggling with anxiety and fear. Kaido tries to take advantage of this, but both Yamato and Luffy manage to pull the Yonko away from Momonosuke. Unfortunately, the force of Kaido's blow sends the dragon falling back down.
However, Yamato is able to remind Momo that dragons fly by riding on flame clouds, which is enough to bolster Momo's confidence to keep him airborne. Once they're floating beside Onigashima, the pair realize that the island is beginning to crumble, with massive chunks of earth falling to the ground down below. Kaido's stamina is finally beginning to wear down and he can't keep the island hovering with his flame clouds for much longer.
Momo predicts that the island will crash into the Flower Capital within five minutes, but luckily, they have a way of keeping it from falling. Yamato knows that Momonosuke can create flame clouds as he did before to keep himself in the air, so he just has to copy Kaido and create enough to keep Onigashima from falling. However, Momonosuke is skeptical he even has the prowess or ability to do such a thing.
Regardless, they can't afford not to try. Even if they do nothing and Luffy beats Kaido, the island will still fall and the casualties will be catastrophic. With what little time they have left, evacuating the citizens would be futile as well. Momonosuke is still hesitant, but luckily, Yamato can knock some sense into them. Stopping Luffy from fighting Kaido is out of the question given how far they've come, so all they can do is try to keep the island afloat.
This was an excellent chapter in that it established a task for both Momo and Yamato. Having a DBZ-esque "the planet Namek will explode in five minutes" threat works in this case, as it's not just the lives of Luffy and Kaido at risk, but everyone still inside Onigashima and the entire Wano population enjoying the fire festival. It's also very fitting that the two people working together to stop this disaster are the future shogun of this country and the man who calls himself the new Kozuki Oden. It's all resting on Momonosuke and Yamato's shoulders now.