Big Mom: "Don't look down on me!
Even right now, I still regard you as my younger brother.
Remember, the day Rocks fell! I was the one who gave you "Uo Uo no Mi, mystical type" (Uo=fish) on God Valley!!
That is the debt you will owe me forever."
Kaidou: "Say whatever you want. Let's just deal with it after..."
Big Mom and Kaidou: "We find the One Piece!!!"
First, I hope Oda don´t wanna come with shit like "Big or Kaido betrayal each other"...
I want it like it is right now, both beeing in one team without thinking of betrayal, I want to see both making a new rock era right now who let the world in fear. I hope a betrayal state out of the question and we seeing both Big mom and Kaido fighting like old teammates.
Second part with is more interesting for me, Big mom literally hint the God valley flashback for the next chapter.
Out of nowhere she make a comment about the day where Rocks fall, god valley, where Kaido get his insane devilfruit power.
And then she said: "remember the day Rocks Fell", kinda a hint what we get next chapter, we seeing the God Valley flashback!!
At least I hope it and want badly that flashback showing us one of the greatest war, the chance are very high though that we get the god valley flashback with end of revealing something about D(Yamato hint it too this chapter).
Last part about Whitebeard.
Yes Buggy said somethings about WB and people are right to ask this out. But remember, this is something with WB call out in Marineford, too much rumors, to much rumors who beeing false about WB. Yes he care for his crewmates but he wasn´t dumb enough to risk their life for nothing. He beeing the strongest, a monster, he call out everything about the rumours and make it clear it was his past not his old version. And let be honest his oldversion wasn´t stronger then Kaido, he most like know it too, why he would risk a total war for nothing?
Oden his brother dead, his family and everyone else death, look at the context what Marco said here. If Ace would be strong enough, WB would lead the crew to face Kaido, with means he Oldversion was simple wasn´t strong anymore. He literally call out Ace while Oden who he respect as most was defeated by Kaido.
Even when it come to Thatch, WB commander get killed and yet he don´t want any revange, because he know it was to dangerous.
Yet he take Ace mistake on his own with risking his OWN Life to save Ace and his crew to make Ace his new captain of his crew. That was his plan for Marineford, if WB would know about Oden beeing caught by Kaido, he would go their too.
The context is important, to much rumors with WB himself call out manytimes, Kaido the strongest one also in wano, a war would be take too much life and WB didn´t want risk it for "nothing"