Board Thread:Questions and Answers/@comment-107.130.244.247-20141220085909/@comment-213.140.59.156-20141221211510

Actually, the nation system in Code Geass by the end is a little more complicated than that.

The UFN (United Federation of Nations) is the structure Lelouch, as Zero, created to oppose Britannia. It is a political union, where all nation members abandon every military matter, and the Order of the Black Knights became the army who ensures every member nation's safety. When Lelouch became Emperor of Britannia, he abolished the numbers system and freed all the areas (it was just the first step). In order to conquer the world, Lelouch forced Britannia into the UFN by taking the members hostage first, and by making every force in the world submit to him (OBK and Schneizel). The neutral territories (old areas freed by Lelouch, like Japan) probably got integrated into the UFN, and all the UFN nations are turned into Imperial Colonies.

By the end of the series, just before his death, Lelouch is presented as the chairman of UFN (Kaguya's position), Black Knights CEO (Zero), Emperor of Britannia.

In other words, everything is prepared, so that they just need to remove him to establish the world order he wanted (but could never achieve because Britannia was opposed to it when he was Zero, and it was just plain impossible when he became Emperor for more reasons than we can mention.). As a conclusion, Kaguya takes back her place as UFN chairman (the political union), Zerozaku becomes OBK's CEO (internation military forces), and Nunnally becomes the Empress of Britannia (the powerful Empire who needs to begin working towards diplomacy by joining in with the UFN... Though with all her country's past, Nunnally has a great load of work in that regard.)

However, I still don't think of it as realistic, but it is realistic enough for Code Geass. I'm one who think that realism pretty much went to hell by the end of the first season, and the R2 has a less mature tone to it, but it still makes some sense, I guess.