User blog comment:Dinosel/Chapter 871: Big Mom used thunderbolt... It was super effective!/@comment-30649965-20170706175102/@comment-30395642-20170706225108

My theory is that Big Mom will follow Luffy and friends to Wano,  I doubt she's just going to let him go even if they escape Whole Cake Island, so I think  we'll end up in a 3-way conflict between the Big Mom pirates, the Beast Pirates and Luffy and his allies.

Oda's apparently been teasing something big that will supposedly put the whitebeard war to shame, so I'm thinking a full blown war between the Yonko ought to do it.

It would also explain why the saga is called the Yonko saga beause normally each yonko would be enough of a villain to warrent their own saga so I'm thinking the Big Mom and Kaido arcs will clash properly.