
Originally Posted by
PokeMaster366
Yeah. That would be one big group of strong allies. If we're counting any strong friends from the Grand Line onwards, we have Vivi and her forces from Alabasta, Dorry and Broggy from Little Garden, some soldiers from the Drum Kingdom, the Sky Island forces and the Jaya residents that were taken there by the knock-up stream, the Franky Family along with some of the dock workers from Galley-La, and the entirety of Fishman Island.
My prediction is that Big Mom is going to be a major trigger that sets the Akainu confrontation into motion. After Luffy takes her down, Akainu will see this as an opportunity to lure him out. I'm betting that by this point, Akainu will have already heard about the fact that Shirahoshi is the ancient weapon: Poseidon, as well as Luffy's involvement in the Fishman Island dilemma with Noah's Ark and the New Fishman Pirates. Anyway, in order to lure him out, Akainu decides to kill two stones with one bird by taking some marine troops and invading Fishman Island. During the invasion, and possibly a few weeks before the summit, Akainu will have abducted "Poseidon" and will be planning to (if possible) weaponize her power and use it to wipe out all pirates on the day of the summit.
Later on, a Fishman will have showed up to see Luffy and tell him about the attack that happened as well as what happened to Shirahoshi. This is where Madame Shirley's prediction starts to come to light. Because Luffy defeated Big Mom, no big names are available to protect Fishman Island now (since Luffy is now claiming the territory). Sure, Luffy may be strong, but Akainu actually wants to pick a fight with Luffy and kill him as a way to shake Dragon's resistance army as well to the point of it being easy to pick off at leisure. Akainu would have a reason to destroy the island and be able to claim that it's for the "greater good of society." Altogether, it's a Xanatos Gambit. If Akainu attacks Fishman Island, he'll have destroyed an island allied with pirates and have one of the Ancient Weapons in his possession. If Luffy does not take Akainu's challenge, Akainu will have the power of Poseidon and he'll use it to wipe out all pirates. If Luffy does respond and goes to fight Akainu and the Marines, there's a high chance that Akainu will kill Luffy. Even if the Straw Hats save Shirahoshi, if Luffy dies in the process, Dragon's army will be shaken by the loss of his son, and the resistance will become relatively easy to pick off, thereby putting the Marines in complete control again.
tl;dr. :P Long story short, if Luffy beats Big Mom, Akainu will kidnap Shirahoshi and destroy the island in the process, Luffy will go to challenge him, and if Luffy dies in the process, the whole world goes to the Marines and Hell.