Doing a bit of reading on Planetizen, on an article talking about sprawl repair. The naivite is a little bemusing. Specifically, the McMansions and drive-thru redevelopment.
Awkwardly, much the low-density street development is not worth saving--cheaper to scrape the site and redevelop then to add a facade of new buildings around it. Likewise, the mansion retrofit is unlikely because doing so would require the cooperation of 8 different property owners--a recipe for failure.
Redevelopment authorities sprung into existence for this single purpose--mitigating the problem of parcel fragmentation through land assembly. (Nevermind that their mis-regulation led them to become engines for cities to speculate in real-estate development).
Parcel fragmentation is a big problem in Detroit. I was talking to Dr. Joanna Ganning, who is an expert in 'Shrinking Cities'. Apparently, for all the Rustbelt cities, it's common for half the city to be a successful metropolis, and the other half of the city to be a run-down ghetto of abandoned buildings, un-maintained streets, poverty and crime.