I think Luffy will defeat 2 Yonko to trump everybody else beating just 1. He will beat Kaido and Shanks.
The K/SA/BH alliance altogether will probably join together to defeat a Yonko. This Yonko, I believe will be Big Mam. Then they will either battle over who will take her place, or submit to Kid becoming the new Yonko. Big Mam at this point will probably be Luffys ally once she figures out they knew Lola from Thriller Bark and are friends with her.
This will anger Luffy and make him want to kick his ass, but will either cross paths with Drake on his way to take him down as well, or Drake will beat him to the punch and defeat him himself, and decline the Yonko position shortening it to 3.
EDIT: Messed up on that part. Drake won't be concerned with taking down Kidd, but will be more concerned with Kaido. So he will cross paths with Luffy on his way to defeat him and they will either form an alliance or challenge each other to beat him first, or something else. But Luffy will still take the kill.
Drake can't be the one to defeat Kidd, because he wasn't part of the Worst Generation 3 when they all squared off against the marines. So since he's already had his interaction with Law, next will be Kidd and they will not get along well.
Then Capone will come through and somehow snatch a Yonko, or War Lord seat since Mingo will be removed. Smoker, or the new War Lord will defeat him.
Not sure where Jewelry Bonney will come in, but she will probably meet either Drake and duke it out with him or challenge Capone and lose, to hype him up. Something tells me she will cross with Zoro and the SH again, since she saved him that time at Sabadoy.