You've got a point to a certain extent but in a lot of mid size cities the downfall started back in the 1960s. Cities that once had thriving downtowns saw a lot of their traffic move to the suburbs with the advent of shopping malls.
Throw the rise and merger of many of the department and speciality stores that dominated the areas, along with loss of major industries. While many cities have tried various solutions nothing seems to stick. I think it goes beyond religion as local churches look like they are aging out..giving way to Mega Churches. Which to me promotes the loss to the feeling of community in favor of corporatism. (I realize I'm broad brushing here)