The suburbs aren't one thing, and this type of pattern is going to vary quite a bit from place to place, depending in part on when the inner ring suburbs were built. Still there is the basic issue that older suburbs are having to deal with legacy maintenance costs, changing demographics, and local resistance to land use/zoning changes that are potentially self-defeating.
I see a lot of boarded up strip malls and houses in places where that would have seemed very unlikely a couple of decades ago.
