I have to agree with Al here. The only real way to "fix" Detroit is to raze the central business district along with the most severely dilapidated neighborhoods around it and start from scratch. The core of the city has no appeal to outside residents, even without the crime and poor education system, beyond the low price of housing/cost of living.
I think it would be more beneficial to the non-wasteland neighborhoods to have designated drug districts in the post-Armageddon neighborhoods of Detroit where the sale/use of drugs is explicitly permitted as opposed to just permitting it across the city. Paramedics would be on stand-by there and clean needles would be available to make sure that complications are minimized. Yes, I stole this idea from the Wire. You have to admit it's pretty novel.
Open buildings rather than Areas where drug use is allowed, and have medical staff in them. Something like Insite in Vancouver but with drugs being sold there. Also add security there so that nobody leaves the area with hard drugs. I am not sure what's up with the hate on CBD though, they are ugly to a certain degree in every city. Why raze it if people want to use it? Better off trying to rebuild Detroit from CBD with medium density buildings stretching outward. Something like Copenhagens 5 fingers plan with wilderness or parks in between the fingers.
That would kind of defeat the purpose of using the change in policy to save money, no? I agree that systems like Insite is a great idea and that we should take it to the next level here. Case studies in Europe have shown that it works splendidly because use is reduced dramatically through them (it's no fun to do drugs in a medical facility, apparently) and fatalities are non-existent.
So that Detroit can have a change in image that's conducive to attracting new residents of course! Detroit's CBD in particular looks/feels like an industrial wasteland and because of that, there's no impetus for neighborhoods around the core to develop as attractive residences.