A trend in post timeskip arcs that I can see forming is the ‘Supernova + Straw Hats vs. Super Tough Opponent’. Trafalgar Law is a Supernova and the Heart Pirates teamed up with the Straw Hats in the Dressrossa Arc.
Law and Luffy are just friends anyway, but the Heart and Straw Hat Alliance could have been the first instance of the ‘Supernova + Straw Hats vs. Tough Opponent’ trend.
Then Capone Bege teamed up with the Straw Hats to attempt to defeat Big Mom.
Now:
-Eustass Kid is already with Luffy and there seems to be mate-y rivalry going on
-There are 9 Samurai destined to avenge the Kozuki Clan, so far there are 5 Samurai. I think there is a real possibility that the 4 other Samurai are Nekomamushi, Inuarashi, Zoro and Killer (the first mate of the Kidd Pirates). Killer is a blade user and could fit into the Samurai mold in his Wano form.
-The presence of Jewelry Bonney in the Revolutionary Army’s story line looks like it could be lining up another Supernova and Straw Hat alliance against a common threat for the next impending arc, confirming the ‘Supernova + Straw Hats vs. Tough Opponent’ trend.
Problems with my theory:
-We don’t know if Hawkins betrayed his alliance with Kid and is working with Kaido because he wants to, or if seeing his ally getting crushed scared him into doing Kaido’s bidding as a slave, because he knows he can’t survive a battle with Kaido. If Hawkins and Kid are in Wano, where is Apoo? He is an underling of Kaido like Hawkins but we haven’t seen him.
-X-Drake seems like he loves being a Kaido underling, it seems like there is no chance X-Drake is working for Kaido against his will.
Anyway it’s possible that Drake is only working for Kaido to achieve his own goals. He was a former marine. He totally has an upstanding moral code that’d run contrary to Kaido’s crew. And I think it’s pretty clear at this point that not a single Supernova captain is the type to work under somebody else.
One Piece has always been about the change of out with the old and in the with new, and Luffy is the herald of the New World order, the future free of corruption and tyranny (but still plenty of piracy). It makes thematic sense that the Worst Generation team up to beat all the older, aging powers in the New World.
*Theory by c4t4ll