And it would be difficult?
1- Adding new types of zoning and density
2- Adding new building rewards that are mutually exclusive (not only in pairs, but in trios and more...). I know that some kind of exclusivity can be done with them, i.e the major statues, but IRC they was some kind of bug that allowed you to bypass the restriction and place both male and female gender.
If this is possible, opens up to a lot of possibilities (just thinking about it, it's not that actually will do it or ask for somebody to...). Basically I'm thinking with a "city specialization mod", tying the building rewards, to some kind of zones and/or densities.
There's some mod in this direction, if this is possible (also if it is only the 2 option, with the normal zones)?