One thing we are all waiting for is the Tournaments. The game is staling in the matter of new features and new use cases for the users so if any development can be done in this direction it would be great.
Adding new buildings will help as well with the economics from the game and one that I am thinking is betting houses to allow users to bet on the outcome of a game between any two teams (that have enough players to compete). This would bring virtual gambling to the game and allow even those that are not players to participate in this ecosystem.