I'd like to see a new game mode. Basically, there is a big map with territories. Each time a player attack's another player's territory, they are linked to a new game with a different map that shows the territory they are invading in high detail. So taking over the main map would take several battles in the smaller maps.

I've often pondered the same thing.

Would it be a custom scenario?
How will world map armies translate to local?
What of your income on the world map?