I don't know if this would be possible, but how cool would it be if the game released with two servers that were both different parts of the world, then in one of the future expansions they mashed the two servers.
It would be us like discovering new areas and see how the other side advanced. Then the cultures and technologies could combine. Think of how cool it would be that in an expansion they collided the two servers then we got to 'discover' the other culture/land/technologies of the other people and if one side was totally not keeping up with the other side, it may turn into a genocide.
The only thing is people leaking information about the other side. Which would make all of this mute.