Not really surprising, given that there's really no reason to live anywhere else in Illinois outside Chicagoland.
Kendall is very much part of Chicagoland. The growth in the 2000's was largely for bedroom communities serving job centers in Aurora, Naperville, Downers Grove and Oak Brook - basically southern DuPage and Kane counties. As the effects of the Great Recession on housing are abating, that growth is starting up again.
The estimated Chicago growth is primarily in redeveloping neighborhoods adjacent to the Loop and an influx in immigrant areas. If this estimate is like the ones in the 2000's then it will have underestimated the population loss from traditional black and white ethnic neighborhoods. It wouldn't surprise me if the net Chicago growth was overestimated.
