Gentrification vs Decay

I found all three of these articles to be very helpful in understanding the issues surrounding gentrification and redevelopment.  I thought it was very interesting how gentrification tends to occur in multiple waves in the same area that the first set of gentrifiers get a taste of their own medicine when even more affluent people begin to move into the neighborhoods.  This was especially apparent with the Wicker Park Artists.

One thing that I continually wonder about is whether or not the process of gentrification can happen in reverse- that is can a neighborhood decline? I'm pretty sure the answer is yes, but what I think is fascinating about this is the different forces that are driving some neighborhoods to "decay" and other to "flourish."  In an ideal world the market would not be corrupted by race or class and yet this is pretty much what causes one neighborhood to decline and another to flourish.  For the most part when whites move into an urban neighborhood it causes it to become gentrified and when minorities move into another neighborhood it causes white flight and the neighborhood to go into decay.  So if both of these are true then the real issue is the uprooting of social networks of poor minority neighborhoods due to gentrification, but the reverse is not true because middle class whites choose to move out of neighborhoods that are starting to "decay."