Since Luffy decided to go rescue Sanji out of his current predicament, we can expect that at least three mini arcs will happen before the real showdown against Yonko Kaidou:
1) Luffy will face-off Big Mom (more like a animated meeting) and the Vinesmoke family
2) Some of the Straw Hats will be fighting Jack before heading to Wano
3) Master Nekomamushi will go recruit Marco, possibly running into Edward Weeble a.k.a. Whitebeard Jr.
4) .....reserved
This post is really about the first point raised above. I think we're in for a big surprise. Let's get started then:
