You hear the same thing out of the armchair planners in Buffalo, many of which still believe in silver bullet fixes.
One thing impressed me about Detroit's residential neighborhoods; where they are intact, the housing is gorgeous; solid, brick/frame Craftsman-style housing from the 1920s, most of which is architecturally intact. Buffalo's mostly frame vernacular housing stock from the same era is altered beyond recognition. The intact portions of Detroit's bunalow belt seemed to weather the aluminum and vinyl siding craze far better than Buffalo's equivalent neighborhods. Detroit also had the benefit of somewhat larger building lots and shorter blocks than Buffalo. Buffalo's extremely dense single family-dominated bungalow belt neighborhoods made for some vibrant shopping districts in their day, but the residential blocks aged poorly for the most part,
Detroit bungalow belt (Chandler Park):
http://g.co/maps/cfmkz
Buffalo bungalow belt (Kensington; my childhood neighborhood):
http://g.co/maps/39yz4
Shrink in a smart manner, concentrating its population into those remaining intact neighborhoods, would be a great start.
A few things Buffalo has that Detroit doesn't: ethnic and racial diversity, decent public schools in lower middle class and better-off neighborhoods, old money families and their accompanying institutions (exclusive private schools, private clubs, etc) which remained in the city for the most part, and vibrant hipster/urban mommy-friendly neighborhoods like Allentown, North Buffalo and Elmwood Village. The "blue ghetto" of police officers and firefighters remains in the city limits. In the Buffalo area, the best restaurants are generally located in the city more so than the 'burbs. This may sound politically incorrect, but whites and Asians don't consider Buffalo off-limits in the same way their peers in southeast Michigan consider Detroit. White and Asian Detroiters are a curiosity; in Buffalo whites and Asians don't register as out of the ordinary.
The ANC in post-apartheid South Africa acknowledged that they needed the white population, and their money and skills, if the reborn Rainbow Nation was to have a fighting chance at success. What about Detroit's city leaders?