I think Blackbeard will come to Wano with the Revolutionaries in tow following them. We know Blackbeard set out to get something that the World Government is ignoring. And with his interest in devil fruits, where is there a bunch of devil fruit users that could die and have their fruits reborn?
With recent revelations, if Who’s Who is the 10th Blackbeard Titanic Captain in secret (see the complete theory here), he could have told him that the World Government wanted the Gomu Gomu No Mi in the past. Not to mention all the crazy devil fruits at Wano right now, perfect for a known devil fruits hunting crew.
Also, there’s the Four Symbols theory! The four symbols are the Azure Dragon (Kaido), the Vermilion Bird (Marco the Phoenix), the White Tiger (Yamato’s devil fruit or Luffy’s Gear 5), and the Black Tortoise (also called “Black Warrior”, Blackbeard!).
These four mythological creatures are often shown as opposites, Dragon vs White Tiger (Kaido vs Yamato/Luffy) and Phoenix vs Black Warrior (Marco vs Blackbeard). The Black Warrior is depicted as a tortoise and snake together. Patient yet knows when to strike, just like Blackbeard patient on Whitebeard’s crew, to strike at Thatch, Ace, Impel Down prisoners, Whitebeard’s Gura Gura no Mi devil fruit and Whitebeard Pirates’ territory. The Black Warrior also has 2 bodies, Turtle and Snake, Blackbeard is “them” and has 2 devil fruits. It seems to just fit for me.
The Revolutionaries also coming just made sense to me as I thought about it. Blackbeard attacked them so they want to stop him now. Wano is where the black market weapons that Joker was selling and that the Revolutionaries were trying to stop are produced.
Sabo is in danger and this could be a way Luffy is told about it. They make a convenient way for Luffy to not fight Blackbeard right now because he has to go save Sabo and maybe Vivi.
Vegapunk might be at Wano with CP0 right now too and might be a Revolutionary himself, he could return to them here.
I guess this would likely take place in a ‘Post Wano Arc’ and could be a great way to set up the ‘Laugh Tale’ arc where the actual fight vs Blackbeard will be.
*Theory by Puzzlephant