Demographic numbers often require a bit of nuance to parse. I am reticent to mention the latest census numbers because they represent a small snapshot in time. While it is true that Chicago lost population in the 2010 census, the previous ten years is in many ways a watershed decade for American society. Just look at Las Vegas' numbers: 22% growth over the last 10 years compared with Chicago's 7% decline might suggest that Las Vegas is the city of the future and doing much better overall. So to simply look at population every ten years and extract from that policy might be myopic. In fact Las Vegas has been doing poorly for almost half a decade.
One new tool for parsing the numbers is from Forbes, and I've captured this bit of data.
As you can see, the trendlines for Chicago are converging. The real questions are what is driving this convergence, how long will the trendlines extend, and what will that mean for Chicago over the next decade?