An e-mail on that post about American views of France and the so-called European "death-spiral":
The banlieues are among the most multi-ethnic areas of French cities. There was nothing in the recent riots that suggests an intifada on the Seine. If anything, I would say that they were more marked by adherence to a French version of American urban culture than anything Islamically inspired.
France is, bizarrely, often cited as both a demonstration of (and a warning against) excessive multiculturalism and as ridiculously strict on assimilation (often in the same article). Reading articles about Europe's immigration troubles seem to suggest that we're damned if we do and damned if we don't.
One final and slightly unrelated point, the focus on immigration is not a European thing but an old European thing. The former Communist bloc states have far lower birthrates than most of western Europe and are currently
suffering something of a brain drain, with the young and reasonably well-educated moving to Western Europe. I think the mix of net emigration and, in some cases, an already declining population roposes are a more worrying demographic problem than Western Europe's flat-lining.
Some more background on the French model in this Brookings essay.