In the midst of dynamic real estate capitalism, persistent social inequality and extended investment in public works, the struggle for space between promoters, low-income residents and other land uses is resulting in complex urban landscapes that contain unexpected opportunities for sustainability and better quality of life. I will assert that the traditional segregation pattern of Latin American cities is undergoing a radical transformation towards lower-scale forms of residential segregation, where decreasing physical distance between people of different social condition is combined with the resort to fenced or walled type of designs. Forces fuelling these changes include the quest for land rents on the part of a powerful real estate private sector, and the urge on the part of the vulnerable households to accomplish a better “geography of opportunity” within the city. The social context that sparks these changes and effects –that makes of segregation a real menace, even a decreasing segregation—is formed mainly by labor insecurity (unprotected jobs) and political marginality (the virtual disappearance of political parties’ activity from low-income neighborhoods). The urban complexity that is exploding in large Latin American cities under this environment, should be assessed in its potential for social and environmental sustainability, and not only in the inequalities and environmental problems that become visible, as usually done.