I guess it will all depend on scaling then. Does the map have 40 cities, or more? Do half the cities appear on my starting continent?
Does it even count if i took 5 cities in previous ages? Or does the victory condition mean i need 20 points worth of cities only in modern era, regardless of the number of cities i took in previous eras?
Does city population make the city's defenses stronger, like in previous games? Even with many districts, if the pop is low, it could make it easier to take such cities, compared to an agrarian high pop city with fewer urban disctricts.
There may be some cheesing strategies to deal with unhappiness. Like, oh i am 4 cities short of victory. I will place my armies all around these 4 city districts and whittle down their defenses. But won't actually take them until i am sure i can walk into all four on the same turn.
Is unhappiness added per conquered district or per conquered city?