The lawns of modern houses are imitations of those found in agricultural estates, grazed by rabbits or sheep.
Back yards are shadows of their former selves, in much the same way.
The attention and expense of maintaining this land is more than many homeowners can afford, especially those whom the recent bubble has saddled with too high of a mortgage.
I imagine that many beleaguered homeowners would rather sell the open parts of their property than face foreclosure, especially if they were allowed to use the land for recreation. I also imagine some enterprising businessmen would like to get into the organic produce business, if only cheap agricultural land could be made available closer to the city.
The farmer could pay a modest fee for certain household waste products: greywater and rainwater, slop and compostables, perhaps even furnace exhaust for use in a greenhouse. The homeowner could pay a modest monthly fee for some of the produce. The lion's share would be shipped in to the city, of course.
Some laws would probably have to be changed in order to make this possible, and some fences would have to be built for the sake of privacy and to contain grazing animals. I'm eager to hear what other obstacles stand in the way of such an idea. But I'm very excited by this possibility.