No, they were born in France. They didn't immigrate to France.
By people who have legal residence in France? Are they for the laws banning burqas, by any chance? How many that are pissed off about the law are citizens by birth? Of those that are citizens by birth,
how many are not treated as outsiders?
So who gets to choose what that national identity will be? We already saw what Europe did before with that route. It was called WW2 and it motivated a genocide.
Those with economic and political power. I would not say it motivated a genocide, though. A crazy man motivated genocide, using economic imbalances as his ammunition, and against a people that actually make it a point of their religion to assimilate. It was greatly helped by Germany's history of indoctrinating its populous to think as they are told, which is something we do a bit too much for comfort, as well. The chances of going anywhere near that route are slim to none; and, if they do,
somebody will stop them. A video can travel in mere seconds across the globe, now--everyone will know the score, well before it could even get to the stage of ghettos.
A lot of immigrants in France come from countries that France destroyed through its harsh colonialism and slavery. These people are going to France and building it and providing it a future with new potential French citizens, especially in light of Europe's low population growth issues.
Hence thinking it will get to violence. If you can accept that "traditional French" treat their traditional culture as something higher than themselves, and thus also higher than those of their lower classes, who are not of that lineage, it makes sense. They want people to either become what they see as French, as they fear their culture no longer being what they view it as. Backwards religious sects gaining power would certainly be something to fear.
Those who seek to stop change will fail in their particular goals, on the one hand. On the other, is it wrong to defend that which you have proudly worked to uphold? I think both sides are somewhat right (upholding rights, treating a history of rich art and politics as sacred), and also fairly wrong (denying rights, racism). France is going to take it to a crisis, which is also something they have quite a history of. When the dust settles, they'll all have to get along with each other a little better, and the extreme sects they are particularly targeting will be outed.

I don't see a population breakdown, there
(or, annoyingly, anywhere--apparently France has some laws that indirectly get in the way of it). From what I understand, if someone is born in France, by legal residents in France, they are granted automatic citizenship. otherwise, they have to somehow earn it. The most I can divine is that, in recent years, they have gotten quite a few million people that they have not granted citizenship to. That still leaves many questions, and how long and how many practice Islam doesn't have a lot to do with it
(someone can fully assimilate, yet still practice this religion, correct?).