@King:
Wouldn't RPG logic dictate him to fight all the subordinate ranks before the Big Boss? Luffy didn't need to beat an officer and an executive officer in order to fight Doula Mongo after all.
Which is why this whole "no one between Luffy and Kaidou" is a pointless thing to discuss.
So what if Luffy just jumps directly to Kaidou after beating Jack a few arcs earlier? Isn't that the point? I'm sure there's plenty of people who could be found in the gap of power between Kaidou and Jack. And I just listed some of them.
I doubt Luffy will defeat Emperor (Kaido, Big Mam, Shanks, and BB) or Admiral soon, thats too far. You know how the power of Emperor and Admiral. I think Luffy would meet his father Dragon before he colud beat Emperor and Admiral because maybe Dragon will train him or gave him something else.