That's a good idea with the Outposts, you could even make it so some cost more than others to maintain and also implement an income system from the ops. For instance, fortresses could have a maintenance cost that is higher than their income, factories the opposite, etc. This would add a certain strategy to the acquisition of ops as well as make the economy slightly more dynamic. Granted, I'm no programmer so I have no idea if it'd be realistic to implement this sort of change, just food for thought.