I think it will take more than 120 chapters:
Vegapunk,Revolutionaires,Ancient Weapons,Laught Tale,Emerald city,Rocks flashback,Elbaf,Road Star,God Valley,Uranus,vs Shanks and BlackBeard,Shiki's plot,Enel's comebak,Straw hat dreams,Imu,Reverie conclusion,SSG,Mihawk vs Zoro and more stuff i'm forgetting.If Oda manages to fit all this in 120 chapters,this is going to be the best manga finale ever.So much stuff in so little time.I hope Oda delivers and makes the best Shounnen Saga ever.