Okay, Adult Momo will definitely happen and the "Momo kills Kaido" possibility is REALLY HUGE after this chapter.
Oda basically retells the Momotaro story again.
Momonosuke = Momotaro
Luffy = Monkey
Yamato = Dog
Marco = Bird
Kaido = Oni.
Momonosuke will most likely deliver the final blow to Kaido, ultimately avenging his father, his country with this move. Momo will do what Oden couldn't do before.
Also, Momo will never turn young again, this transformation will be permanent. Thus, there is a chance that Momo will lead Wano after Kaido's defeat while Yamato might really join the strawhats...