Right now im 50/50 on it with Luffy either fighting Kizaru or Saturn imo
Id be happy with either tho tbh
As for luffy vs akainu idk anymore
If luffy fights either luffy vs akainu automatically loses some hype. Then their the possibilty of sabo or someone else fighting him. On top of that luffy beating kaido's magma dragon and oda would have to give him an even hyper attack
If luffy really does fight akainu i can't help but think he might be the blueno to imu's lucci tbh