:::There you go with your useless links to unrelated guidelines: WP:Fancruft, WP:Coatrack, and WP:Soap. Also you are back to the Atlanta synthesis, and now Chicago, neither of which has a bearing on this issue. If you think this article should be deleted, then put your back into it and nominate it for deletion—but don't be surprised at a "speedy keep" result. Your crime section complaint is supported by a link to a public relations announcement in prnewswire.com? Not reliable.  
 :::The only relevant points you have made are that POVTITLE calls for neutral titles, and that "good suggestions" were made in the form of "Demographic change in Detroit" and  "Social history of Detroit in the 20th century." 
 :::*WP:POVTITLE: "Conflicts often arise over whether an article title complies with Wikipedia's Neutral Point of View policy. Resolving such debates depends on whether the article title is a name derived from reliable sources or a descriptive title created by Wikipedia editors."  
 :::As you can see from the list of reliable sources I have brought forward, the title "Decline of Detroit" is used by a great many sources. 
 :::If you initiate a WP:Requested move to suggest either "Demographic change in Detroit" or "Social history of Detroit in the 20th century", you will have a hard uphill battle trying to prove either of these is used much more often than "decline of Detroit". Not one editor here has pointed to reliable sources in an attempt to show that either of these titles is better than "Decline of Detroit".