In cities across the country, groups of people are protesting gentrification by directing their ire at the businesses they feel are responsible. But experts say these groups are facing forces much larger than gentrification — forces that, if left unabated, could mean a change in the types of people and businesses able to survive in urban areas. I wrote about this phenomenon for Crain’s National. The piece has since been used to teach Harvard University’s sociology students about gentrification and housing in the American city.