Here's what I think is going to happen in France. In the short run, there will be a crackdown on the rioters. In the long run, the Chirac government is finished. It will be replaced by a more conservative government. There will be a much more restrictive immigration policy instituted in France. Less money will be spent on low cost housing. Some of these low cost projects will be torn down. There will be a new housing policy of dispersing this type of housing - smaller units over a wider area. Some of the disaffected Muslims will leave.
I think that is a quite probable scenario you outline. I wonder if this is not a deliberate strategy by Sarkozy, i.e. by cracking down in the "no-go" zones, he knew there would be an ugly reaction, which would bring to the surface and to the attention of the average French voter the festering sores that these muslim ghettoes are. This pushes the voters to the right, although probably not all the way to Le Pen, given the very high percentage of marxist and socialist voters in France. It may even split the French socialists between those who want to limit immigration and clean out these no-go zones and those that adhere to the more traditional socialist policy.