At the Reverie there will be many major topics, but I only want to speculate about the Countries which will be excluded because of “crimes” in the past. Here we go:
1. Germa Kingdom
Ok, that has happened already! Monkey D. Dragon said that Germa was ejected from the World Government after the Big Mom incident.
2. Sakura Kingdom
We see Dalton as the new King of Drum Island after Wapol. At this Reverie Drum Island will get expelled from the World Government. The reason is the flag Dalton chose for his Island -> a pirate flag! Furthermore Wapol tries to find a way to bring down Sakura Kingdom.
3. Amazon Lily
At the Reverie the Shichibukai-system will be disbanded and Boa Hancok will lose her warlord title. This will be a big problem for her and she will be treated like a normal pirate and a criminal. Amazon Lily will get expelled!
The reason why Alabasta will be expelled is because King Cobra will ask the World Government a very dangerous question: He will ask them about the Poneglyphs, which will be a big incident. Alabasta -> expelled!
King Riku and Viola are on the way to the Reverie together with the Tontattas. Leo and his friends are part of the Straw Hat Grand Fleet! King Riku warned him “Once we get to the holy land you cannot speak of this (to be a pirate)”. When the World Government will find out that King Riku is cooperating with pirates -> expelled
6. Kano Country
Sai and his family are the rulers of Kano Country and at the same time part of the Straw Hat Grand Fleet -> expelled!
7. Fishman Island
The Fishman Island will not be allowed to go to the surface and Neptune will be disappointed. Fishman Island will get expelled because of the possession of an Ancient Weapon (if Caribou told the World Government) and Shirahoshi could get captured at the Reverie.
*Theory by Wolfram87