I thought this before, but after Oda almost shoehorns that Whitebeard flashback into the story in Chapter 999, it’s even more possible than ever.
Oda also made Old Whitebeard to pass the torch to Luffy even in the pre-timeskip battle, right after Luffy used Conqueror’s Haki.
Not long ago, Ace tried to persuade Whitebeard to invade Wano Country to fight Kaido, but Whitebeard rejects Ace’s request since Marco says there would be major casulties on their crew if they fought Kaido, and Whitebeard says Kaido is too strong because not even Oden could defeat him.
This was after Ace become the 2nd division commander in Whitebeard’s ship, meaning that it wasn’t so long before the current story when Luffy started to his journey.
Essentially, the expected things that ”strongest” Old Whitebeard had to do, or couldn’t do in chronological order:
01- Not being able to fight Kaido at Wano and not being able to force Kaido out of Wano, despite Ace tries to persuade them to do it.
02- Not being able to defeat Shanks, even when Shanks challenged Whitebeard in Whitebeard’s own ship and before when Shanks KOed some of the Whitebeard Pirates with Conqueror’s Haki.
03- Not being able to defeat the Marines and couldn’t save his crew member due to getting too old and sick.
04- Not being able to defeat Blackbeard and Blackbeard Pirates.
05- Then he mentions about finding One Piece and the big war against the World Government.
Right now, Luffy is following the same first step;
– Luffy is going to accomplish what Old Whitebeard couldn’t, and defeat Kaido and force him out of Wano, saving Wano.
If the route will be the same, then:
– It’s possible that Luffy will defeat Shanks next, since Oda indirectly said Shanks will be the next target, said the next year will be Shanks’s year. And Shanks was the only living person in Kaido’s vision for Luffy after getting hit by Red Roc, probably Oda wants to highlight Shanks as the next opponent, rather than Blackbeard or Big Mom.
– Then Luffy will defeat the Marines as whole and save the person he wanted to save? Perhaps Sabo? The Marines might use Sabo to draw Revolutionaries into battle, similar to how they used Ace, or it could be another person.
– At that point in the story, both Blackbeard Pirates and Straw Hat Pirates will defeat the Marines, and perhaps Blackbeard Pirates will defeat the Revolutionaries as an extra after defeating the Marines, and then they fight each other and Straw Hat Pirates wins by also saving Revolutionaries from Blackbeard Pirates.
– And then Straw Hat Pirates find One Piece, thus they finally reveal the truth about Void Century and they learn why they must fight World Government and they gain enough allies to fight the whole World Government and Imu.
– Then they defeat the World Government and Im alongside with Luffy’s allies, and with the Remnants of the Revolutionaries. I believe the Revolutionaries must be weakened like Whitebeard Pirates were weakened after the war with the Marines and Blackbeard Pirates, since it would be hard to highlight the Straw Hat Pirates over the Revolutionary Army in the final war against World Government and Im, if the Revolutionary army is at full force.
If this happens, then Oda specifically uses the same chronological order for Luffy, by making Luffy to accomplish the things that Old Whitebeard couldn’t do.
Even though Admiral fans always talk about how the Marines will be the final villains, I think taking out the Marines and the World Government separately would be better for Admiral fans, even though they always believe the Marines will be the Final Villain, but consider this, if the Marines only fights under World Government forces in the final war, then they would be overshadowed by the full force of the World Government, the focus would be for unknown characters like Im, Gorosei, CP0, Vegapunk’s secret weapons and Kong’s forces, it won’t be focused over Akainu, Kizaru, Fujitora or Ryokugyu.
Don’t forget that the Marines are only the outward face, not the real face of the Government as Gorosei said.