It would be awesome for this game to go towards a realistic fashion, but I think there is a level of impossibility with that.

First and foremost, this is kind of a limited platform for realism. I think it would take something on an MMO level to offer realism, because the world is
persistent.

On a second level any online game is meant to keep the gameplay flowing, to keep the player going, and therefore realism is traded for certain rules. Such things as regenerating walls, not being able to lose your last city, etc.

I know a set of things that could be added for realism though. One is variables. There could be disease outbreaks, violent storms, and also bountiful harvests. There could be roaming packs of bandits.