User blog comment:Besty17/One Piece in 2020/@comment-24769684-20160822173622/@comment-34981281-20160822175614

Dressrosa Arc was over 100 chapters. I doubt we'll EVER see that again. Even the likes of Thriller Bark, Skypeia, Enies Lobby, and Punk Hazard only average ~50 chapters. But let's be generous and say that Whole Cake Island Arc and Wano Arc are going to be 100 chapters each.

~700 - Start of Dressrosa

~800 - Start of Zou

~820 - Start of Big Mom

~920 - Start of Kaido

~1000 - Defeat of Kaido

Seems a little cookie-cutter to me, but actually a lot more reasonable than I expected when I started this comment. I could buy the Chapter 1000 theory.