You may well be right on the German side. I think you are better assimilating them than the French and Brits, plus you have the Eastern immigration.
I don't see it being very pretty in France, in 20-30 years. Even if immigration were to stop today, they have significant growing communities of unassimilated Arabic Muslims. And yes, if I had to choose, I'd take Turkish Muslims over Arab ones any day.
Things are a littlebit more complicated. In difference to other European countries the Frogs have a quite high birth rate. Vive l'amour! Even if you Americans are boiling in anger about the cheese eating surrender monkeys, it is a fact that some of the most beautiful women are from France.
:-)
Therefore they are that attractive to their men that the average number of kids/woman is about 2. Much higer than in all other European countries. To give you a comparison: In Germany and Austria the ratio is at 1.3, Russia and Italy are at 1.2, Spain at 1.1 and the USA are also about 2. (BTW - I will not doubt that those countries have beautiful women too).
Therefore: The French population is stable. There are some pure muslim ghettos, espechially in big towns. Furthermore it has to be said that most of those French muslims are at the lowest end of the social ladder. As uneducated and unemployed persons they will never be able to take over power. It will be interesting to wait for the future political development in France. Maybe you heared about Jean Marie le Pen. The French have a much broader and stable far right wing than Germany. If the political right is provoked enough with torched cars and raped girls I could imagine that the muslim movement in France can come to an fast end...
To me the biggest problems with muslims are boiling in the UK. Low birth rates combined with radical scum from Pakistan that is multiplying fast. Not good.