Detroit burned in 1967. After 5 days, there were 43 dead, 1,189 injured and 2,000 buildings destroyed. That was only the beginning. Ten of thousands of people sold or abandoned their homes and left. The burned out businesses never rebuilt. New businesses did not move in. Other businesses closed or relocated outside the city center. The ripple effects of the '67 riots still go on.
The city is still in freefall. There's no tax base, no industry. The population is a third of what it was. Abandoned buildings and homes predominate.
It isn't going to matter why the people in Ferguson burned and looted those businesses. They are gone. It isn't going to matter what sort of justification people had or made up for their actions. All that is going to matter is that the businesses are gone and will not come back. The people of Ferguson will now look to government to fix things.
My guess is that the government will promise big and deliver just like they did in Detroit.