in lots of games countries play the role of the aggressor, conquering and annexing large chunks of land until the former country is unrecognizable
or suffer enough damage to look like shadows of their former selves
i suggest optional premade name change to the country in case it fulfills certain conditions,
like if italy is reduced to less than 3 cites and one of the cites is rome it can be renamed to rome.
or if insurgency takes over china they can be renamed to "the three kingdoms" (something from the past of china)
nothing too crazy, nothing too long, not ideology based optional and premade by the game creators
can even come with nice lines like:"the people (insert nation here) see the conquest of the enemy and know it is time to fight back, some have suggested starting the change by renaming (insert nation here) to (new name)"

it is optional, i'm sure some people will like changing the name of their country to fit to the game's reality a little bit more
and it dosen't sound like too much changes to the game

i cant delete so ill leave it like this