The Knowledge Economy employs fewer people than those that came before it. Wherever globalization goes, only a small minority will be riding high on the economic tide.
Many of the efforts made to resuscitate dying cities aren't concerned with dying neighborhoods. Sometimes it's easier to just amputate the limbs to save the body.
The demand for labor explains a lot of migration patterns. Where the uneducated once moved to staff large industrial centers, now those with the means and a college education flock to feed the Innovation Economy that is rising from their ashes.