Luffy will be a Yonko of the next age, with for the moment more than 6540 men. But who will be others yonkos ?
I think that Luffy will become allie with Big Mom thanks to Jinbe ( and Lola?), but probably after some fight. Kid's alliance and Kaido will manage a kind of agreement about the tragets. Black beard will turn to his advantage the aiming of Shanks.
So, IMO we will see: Luffy + Big Mom (+Sahnks) VS Kid + Kaido (+Black Beard).
We saw that Kid destroyed tow ships of Big Mom, he was aiming for her personally.Then, he made an alliance with Apoo and Hawkins to traget Shanks.
Even if strategy of Kid, Killer, Appo and Hawnkins is perfect, I think Shanks is too strong for them, also becuse he can be helped by the Phoenix's crew.
So, in my point of view, Luffy will take the head of Kaido, thanks to Law. Black Beard will take the head of Shanks thanks to Kid. Kid could take the head of Big Mom, but anyway, Big Mom also will fall after this war.
Marshall D. Teach will be the only actual Yonko to stay in the game. I think he will find the way to become the pirate's king before Luffy it will be clearly the age of Black Beard.
But 3 others Yonko will appear during this time, first Luffy, as i said he will replace Kaido, The King of Beasts, Luffy will be the new "King of Beasts", he is the symbol of Sun Wukong. Also Every attack of him after the time-skip is named after animals and weapons: "Elaphant Gun", "Grizzly Magnum", "Rhino Schneider", "King Kong Gun".
During the two years, Luffy trained himself in the island of Rusukaina in Calm Belt, here he fought against every dangerous animal during 48 different seasons. Luffy "the King of Beasts" is already announced.
Let's do some parenthesis about the allies of Luffy. after this chapter i finally think that no one of these allies of Dressrosa will join directly Luffy's crew. Not Sai, not Canvendish, not Hajrudin, not Bartolomeo.
Suleiman who joins Canvendish's crew is pretty understandable, he was very watchful during the fights in the Colosseum. Even, he was not able to stop Hakuba, he can read the moves easily, Suleiman knows how works Hakuba, he ll keep an eye on him now.
About Ideo from the Long-Arm Tribe and Blue Gilly from the Long-Leg Tribe, it's pretty logic that they join each others.
They are inspired og the Japanese Yokai: Ashinagatenaga, it's a pair of Yokai: Ashinaga-jin has long legs, and Tenaga-jin has long arms. In the story, they come from two different countries and work together to get fishes.
Lets come back to the Yonk's discussion, after Black Beard and Luffy who will be the others Yonko?
Trafalgar D. Watel Law? No, I don't think so.We know that he has the power to give immortality to someone in exchange of his own life but he will not give this power to Luffy, becuse the manga will become boring if Luffy becomes immortal.
Law is the main card against Kaido, he will remove the immortality of Kaido and let Luffy finish Kaido. It will also shows that it's not so easy to beat a Yonko, they need a sacrifice. Even, if Kaido becomes mortal, it will be not easy to beat him.
Luffy doesn't want this to happen, but it will be the only solution to win 1vs1, Law will die, this tragic event will make Luffy so mad: same reaction it was for Ace. With the memory of Law and his sacrifice, Luffy will finally win against the Yonko after an epic long difficult fight.
The next Yonko is Eustass Kid, he is clearly the best rival of Luffy among the pirates we know, he will take the place of Big Mom, he is the most dangerous of the Supernovas, he is always the more ranked about the bounties.
I agree with the thing which says: Luffy = Gold D. Roger, Law = WB, Kid = Shiki. But i really think Law will die against Kaido by suicide, i mean, the two leaders of each alliances are clearly Luffy and Kid.The people of Dresrosa want to join luffy not Law, Luffy won against Doflamingo not law, Eustass Kid is already too close to Luffy to be a future Yonko.
I also think that Kid is a D and knows the Conqueror's Haki. I have absolutely no proofs of that, but to be the equal rival of Luffy, he will have that, he can hide his name like Law did."Kid D. Eustass" or "Eustass D. Kid'.
In my idea, he will be the only last Supernova to be a Yonko. About Apoon, he can join him or join Black Beard, Basil Hawkins won't be a Yonko but can join Kid or have another future, every others Supernovas will choose the Luffy's side or Kid's side.
About the last Yonko, who will replace Shanks, it is someone we all know, and who is constantly gaining more populatiy in the One Piece's world.
It's Buggy the Clown!! No it's not a joke, let me explain:
Even Buggy was everytime a funny character, he has a important position in the fture of One Piece.
With Mihawk, he is the most close to Shanks, he was his mate in the Gol D. Roger's Crew, he is the good person to replace him.
I think this scenario is very possible becuse Buggy has collected many dangerous men of Impel Down, he became a Schichibukai, even he is not very strong, he is gaining alot of "power" in One Piece.
Mihawk said about Luffy that he has the most dangerous ability: to ally himself with many people
and be followed by them. Buggy has the same power, also his trip in the Oro Jackson when he was young is a very good point in the New World, he knows things.
Buggy was the first serious adversary of Luffy, I mean, compared to Alvida and Morgan, he was more strong, he has beaten Zoro at the begining, he was the first enemy to have a Devil Fruit offers so much possibilities, he will maybe stay a funny character, but he still can be a Yonko.
The value of Buggy is his reputation, Alvida and Galdino joined him, he will recruit others pirates really strong this time. Also, he shares another great skill with Luffy: the luck. Buggy is one of the most lucky characters.
About his Devil Fruit, imagine how strong he will be if he learns how to use that properly, he will have the same effects as a logia does: become untouchable.
So, Buggy will be one of the last rivals of Luffy about The One Piece, even he is funny, he will have his role to play.
All rights go to the maker of this theory.