Carrot - Make living in the city better for people who are in the suburbs

1. Make rent in the city CHEAP/help people find homes in the city who want to be there
2. Make moving goods around the city for families cheap/easy
3. More Parks and play areas for kids (basically make living in the city easier/better for "families" )
4. More transit options
5. Much better transit options for the disabled
6. Make it easy for people from suburbs/far away visit the cities.

Make Farm live more desirable/possible for those who don't love the city

1. Availability of training for farming
2. Subsidies for smaller farmers for crop varieties
3. Get them equipment/ability to share equipment (as economies of scale and so forth)

Stick -

1. Make it harder/more annoying to build "neighborhoods" of single family homes.
2. Incentivize turning lawns/property in suburbs into climate appropriate farms. (IE - less fucking almonds in California that should be a fucking desert)
3. Break Buying/Selling Homes - investment in home ownership must be turned from a goal/purpose for people into "owning a boat"/ Buying a "new car" a huge waste of money that you are doing mainly for the sake of having it.

I'd look at it as a long term thing of removing the things that make suburbs seem better than Farm/City life.