I had once made a thread called Civilization V: Geopolitics proposing a complete conversion of the game that would make it more realistic and fun at the same time. The thread is now dead, but I think that those ideas would have a perfect synergy with this mod. Once the current issues are ironed out we should really get to work on that. A new trade mechanism, based on the movement of trading units themselves "carrying" dummy resources which translate into yields for the cities receiving them as well as gold, should be implemented.