A more probable population of Detroit is closer to 696,000. Also, it would be almost impossible to have the city see a net population gain between 2010 and 2020. Even if the population-loss bottoms out in the next few years, or even sees an upswing near the tail-end of the decade, it won't be enough to offset the losses since the last count. A more plausible population in 2020 would be something in the 600,000-640,000 range.