Egghead Island seems to be the reverse of Punk Hazard.
Punk Hazard is the first arc where the Straw Hats veer off of the Log Pose and they do not follow it again until Egghead Island.
Punk Hazard was a tropical island that got turned into a freezing island by an accident while Egghead is a winter island that has tropical weather because of Atlas’s invention (intentional).
In Punk Hazard, Kin’emon is stuck to a dragon and is rescued by the Straw Hats. In Egghead, Vegapunk is stuck to the Iron Giant and is rescued by Luffy. Luffy even notes the similarity telling us the readers that this is intentional from Oda’s part.
In Punk Hazard we have Kin’emon, a father looking for his son Momonosuke. This turns out to be a facade. Kin’emon also gets petrified and has a fake-out death. Bonney is a daughter looking to restore her father Kuma which is a secret that gets revealed. Kuma currently has many death flags.
Giants play a big role in both arcs with the giant children in Punk Hazard and the Seraphim, Iron Giant in Egghead. The next arc seems to be Elbaf which is the land of giants.
This panel from Punk Hazard where a giant attacks a castle town seems very similar to the Iron Giant attacking Mary Geoise.
Momonosuke appears for the first time in Punk Hazard and there we learn that he ate an artificial devil fruit created by Vegapunk. This is expanded upon in Egghead.
In Punk Hazard, Law swaps Smoker and Tashigi’s body causing Smoker to become a woman. In Egghead, Doc Q turns Law into a woman temporarily which just so happens to be the reverse situation of Punk Hazard.
In Punk Hazard the Straw Hats kidnap Caesar Clown while in Egghead the Straw Hats are reported by Morgans as having kidnapped Vegapunk. The Straw Hats also use York as a hostage similar to how they used Caesar in Punk Hazard.
In both arcs Luffy makes an alliance with a Supernova. Luffy also makes a temporary alliance with the antagonists. In the case of Punk Hazard, it is stated that pirate alliances often end in betrayal, but Luffy never gets betrayed while in Egghead, York is a traitor amongst the Vegapunks with whom the Straw Hats allied themselves with, Lucci also betrayed them and also the Blackbeard Pirates might have infiltrated their ranks.
Vegapunk is Caesar’s antithesis with the exception of York. York seems to be playing the role of Caesar in this arc. Caesar is also a bitter rival of Vegapunk’s.
Going by these similarities and reversals, I believe that Egghead’s ending will be an inversion of Punk Hazard’s ending.
In Punk Hazard, Doflamingo orders Monet to press a switch that will destroy the island killing everyone on it except Caesar. However, because Caesar kills Monet, Monet fails in blowing up the island. I think that Egghead will blow up unlike Punk Hazard and the way it will blow up will be an accident as a contrast to a failed mission.
I believe the power plant where the mother flame is created will be destroyed causing the entire island to get destroyed. I believe this will be done Franky who blew up Vegapunk’s homeland of Baldimore. This is coincidentally called the future country incident.
This will also cause Punk Records to get destroyed. A malfunctioning Punk Records will transmit Vegapunk’s knowledge of the Void Century to the entire world.