I do think the progress in the city of Detroit is starting to translate into overall recovery. Below are graphs showing the loss/gains for Wayne, Cuyahoga, and Allegheny counties every year since 2010. Wayne's losses are the only ones that are consistently trending toward zero. To be clear they are still losses but the amount has steadily diminished every years since 2012. I believe this years estimates represent the smallest losses since the early 1960's which IMO is huge.
I've always thought the situation in Detroit was more nuanced than the other cities, especially since it's metro has only lost about 100k residents total from its peak. I think it's problems are far more political, and driven by fractured regionalism, than economics. The billions of investment going into it's core seems to be translating dividends. I've always thought Wayne counties losses are inextricably tied to Detroits. If Detroit stops losing people, so will Wayne County. It appears to be trending that way.
To be fair I still think the city of Detroit is the furthest behind in its recovery next to the cities it's being compared to. Once it hits a certain threshold I think it's recovery will move quicker.