Some future chapter ideas:
Nationalist and Fascist Governments:
This includes states that are ideologically fascist in that they base their teachings on Mussolini, and those that are just nationalistic. There will be a regular fascist state (probably an ahistorical one), a "good"/functional fascist state (one that is already ethnically homogenous and, because of its circumstances, not expansionist; post-Japanese united Korea? By no means a democracy, but does respect human rights, even if they think their rights are superior), a democratic nationalist state, the Evolan Moskowien suggested above, maybe an Esoteric Hitlerist Indian state, and the rest will probably focus on different definitions of nationhood.
Technocratic Governments:
The main thrust of this chapter is likely exploring rule by different kinds of experts: there will be the expected science dictatorship, but what about a red-flavored one ruled by "labor experts," one ruled by judges and lawyers (that isn't a massive Dredd reference), and maybe a state that is run by an AI (but in reality is run by the people programming the AI).
Colonial Governments:
The main differences will be how self-governing a colony is. We have de facto independent states with some colonial links, like OTL Canada, there are directly-governed colonies, and a lot of states in between. Another interesting colonial government are those colonized by non-state actors; a successful Liberia "colonized" by the American Colonization Society, whose headquarters remain in the United States? There might be a prison colony there that remains a prison colony into the 21st century, so probably not Australia. There might even be a joint Soviet-American lunar colony.
Theocratic Governments:
Runs a large gamut, from a government with an imperial cult (surviving Roman Empire, although a very small one that only has control of the area around Rome proper), to a theodemocracy (you can vote for all of the parties you want, but they are all religious). This would include the black American Protestant state, where the rhetoric of Martin Luther King Jr. would not be foreign, and a technically-secular Holy City of Jerusalem governed by over half a dozen religious movements because the Status Quo applies to the entire city (six Christian churches, Sunni and Shia Muslims, and of course religious Jews; and you thought the OTL situation is a mess!).