I think we will see an alliance between the Heart Pirates and Katakuri and here’s why. Pudding has been kidnapped by Blackbeard and is currently on his ship.
Right now Blackbeard is attacking Law. It’s been a few chapters since we’ve gotten back to Law vs Blackbeard fight but I do not believe it’s finished. First of all Law isn’t going to be killed off screen and I don’t see why he would be captured.
I believe Law will be saved by the appearance of Katakuri and his family. It is possible Brûlée was able to sneak onto the ship through a mirror as I noticed she was the only one not covered in ice.
She will then report back to Katakuri who after the attack gathered his own ship and set off to get his sister back and has followed them to Winner Island. With more people showing up Blackbeard will call it quits and leave saying he can try again later not knowing that Brûlé managed to take Pudding back. This is where Katakuri will meet Law.
So how does Katakuri greet the man who was responsible for his mother’s downfall? I believe he will actually reveal support for Law. Katakuri is a Conqueror’s Haki user as well and this might be his time to lead a rebellion against his mother and take over because the main problem with Whole Cake Island is Big Mom. She’s their biggest defence but she is also doing the most harm to them. We know several of Katakuri’s siblings have been chased away due to Big Mom’s wrath and many of her children do seem to despise her for her cruelty and nature.
Even Katakuri seemed pleased when Luffy got away and hopeful when he said he would come back and beat Big Mom.
So I don’t know if Katakuri would hold a grudge against Law or Kid either.
Now here’s the kicker. I came across this video that explains Big Mom is actually inspired by Napoleon the french military leader her hat homie is even named after him. Napoleon suffered 2 major defeats in Waterloo and Trafalgar. Law’s full name is Trafalgar D Water Law. Napoleon was banished to the island of Elba.. Elba = Elbaf.
Law has the Poneglyps but no translator and Pudding can awaken her 3rd eye. Katakuri wants to protect his family and he’s finally ready to stand up to Big Mom. He will get word that she is in Elbaf and will convince his family it’s time to rebel and protect themselves and each other. He will gain an alliance with Law so that Whole Cake Island can also get another protector as many people will see it as a good time to attack after all the recent failures. Law needs a Poneglyph translator. The two will form an alliance and go to Elbaf.
*Theory by MrBushido56