One Piece started with East Blue Saga,
Oda himself said that He wanted it to last exactly 100 Chapters, to the point He even removed a Chapter of Usopp vs Daddy Masterson so that He doesn't miss that Number, which confirms to us that He has a Pattern in mind that He wants to remain Consistent, this is further demonstrated by Chapter 100 Title "The Legend has Begun", it's as if entire East Blue Saga is actually Pre-One Piece Story.
During Luffy's entire Journey in this Sea, Oda decided to make only Two Characters arrive to Introduce themselves, you can even say that their Introduction was Forced, rather than needed, They were Mihawk & Dragon, who as you can notice by now, are the most reserved Characters ever (Even Shanks failed this Race with them), what's even more interesting is that Mihawk was Introduced in Chapter 50, while Dragon was Introduced in Chapter 100, clearly indicating that their Introduction was part of this Pattern that Oda wanna preserve.
If such 100 Chapters marked the Beginning of their Adventure, wouldn't it make sense that Oda would end their Adventure with a similar 100 Chapters? So i kept checking the End of every 100 Chapters but none of them stood out, not until We reached Chapter 1100, where Oda took Kuma to Luffy's Village, where We are back at Chapter 1 Timeline, that Scene served nothing plot wise except telling us that the 100 Chapters that are gonna mirror First Saga have just started.
To confirm such suspicion, We must find that Chapter 1101 is a reference to Chapter 1 which indeed ended up the case, as it was the Chapter where Bonney left her Island & started her Journey copying Luffy's Punch, exactly like Chapter 1 Ended, and it makes even more sense when you remember that Start of Post-TS is exactly 500 Chapters away from both Chapter 100 & Chapter 1100, so there is indeed a Parallel.
Now let's be honest, would we call it a coincidence if Oda suddenly out of nowhere Introduces a super Major Character in Chapter 1150 just like Mihawk's totally unexpected Introduction? (Both arrived in Chapter 49 btw, but Full Introduction is in Chapter 50), it's obviously not a coincidence at all, So now, i can only expect that in Chapters 1199 & 1200, Oda is gonna Introduce another Lurking Legend just like Dragon was Introduced.
I can even tell you his Fighting Style, He has Powers of all Creatures, basically imagine what Imu is doing this Chapters, but instead of Weapons, He wields Power of all Beasts & Mythical Creatures.