Struggling Rust Belt cities in Ohio may seem a million miles away from tech-corridor creative class communities challenge-wise, and in many respects they truly are. Despite many differences, their common denominator is that neither is sustainable, not really; and in cases at either end of spectrum, this is largely because both lack economic diversity. Whether the scale is the city (Baltimore, Philadelphia, Buffalo on one hand, Santa Fe, Austin, Raleigh on the other), the neighborhood (Roland Park on one hand, and McElderry Park on the other), or the region, important sustainability issues require attention.
In many Rust Belt cities, the result is that it’s almost impossible to balance the municipal budget because of concentrated weakness in urban housing markets that have sagged for decades and pushed out their middle class . In creative class places, the result is that it’s almost impossible to trim the many off-loaded costs of resulting sprawl that owes much the power because of concentrated strength (see William Fischel's still utterly superb Homevoter Hypothesis), and resulting sacredness of certain value-generating cows (like height and open space preservation). The former's concentrated weaknesses have pushed and continues to push out the middle; the latter's concentrated strengths pushed and continues to do the same.
A major system challenge of course is that strengths and weaknesses when super-concentrated become self-fulfilling engines of their own. Genuine (fiscal as well as environmental) sustainability hinges on teachers not living far from doctors and janitors not living far from cops and college professors not living far from machinists, which is not an invitation to have another spatial mismatch debate so much as it is to decide how important the middle really is.
Does form matter? Of course. Height and density are an essential part of any middle-oriented discussion in a strong market, without which the revenue needed to achieve balance will simply be missing. Does product matter? No question. Yards and garages, enough space for kids, and modern conveniences are all boxes that have to checked for families to be a part of any community's future in any real numbers. But middle class flight from weak markets and an inability to buy into strong markets share the common thread of class and persistent race conflict, which is far more central to sustainability than gray water systems and farm to table plans.