Actaea

Well, I also hope that Revan won't create an expansion based on current times, but rather set it in the future or a fantasy setting.

Revan mentioned that the year of the setting is 2015, and most likely, the setting will be almost identical to our reality, with the exception of the states.

How to create the setting?

Various details are not so important; in the worst case, they can be saved in a factbook or one's own memory, and the setting will be based on various parameters + possibly some introductory information from the creator of the state, such as: "My country is a land of freedom with the legalization of gay marriage and a ban on religion; everyone else is an idiot, etc."