I think we've found the possible title for the next volume.
"Yonkou Vs. New generation"
Everything spanning the recent chapters have been about this confrontation, from build up to current events. We've seen a bit of what each side is capable of and how motivated they are to win it.
The Emperors are beginning to acknowledge this new breed of pirates and the rookies are no longer playing "little pirate games."
Luffy looks to be the star of this chapter. He's learned to apply his haki defensively as well as offensively. Kaido wasn't joking when he said he was approaching the likes of Roger, Newgate, Shanks, etc. This is a huge boon, ontop of his natural DF advantages.
But so much for the Emperor's elemental attacks, Luffy and Zoro have means of countering them. Luffy's immune to lightning and can create barriers for the others, Zoro can just cut them.
So far, the two sides are at a stand still. The Rookies are countering the Emperors' attacks, but the rookies aren't able to significantly damage the Emperors. Someone has to give, and I think something tragic might occur to finish off the volume.
Kaido finally remarks on Enma. Everything is coming full circle. Zoro received Enma the same chapter these excerpts released.
Enma has only ever been tamed by one man and it was Oden. No one, not even Oden's trusted vassals were strong enough to wield it. It took a swordsman of relative, if not greater willpower than Oden to be able to. This is how Zoro and Oden's connection forms. It will take a powerful swordsman to help defeat Kaido. Ryuma and Oden are dead, a new generation must rise up in their absence.
Oden's battle is not finished, and there is only one swordsman left who can complete the task he couldn't.