I personally think that Momo will experience the same scene Shirahoshi had in Fishman island...
Where his desire to protect the capital will end up awakening his powers regarding the animals like Zunisha for example....
So basically I think Momo WILL make the island stops, BUT not through his flame clouds, as I think it will fail....I think his desperate feeling will be transmitted to animals as big as Zunisha and sea kings to appear and stop Onigashima from falling