Racism is, then, a critical element--perhaps a dominant concept--relative to these concepts. If European Muslims or New York City Jews are inherently subversive, undermining legitimate decisionmaking processes in political and social life, how can anyone who belongs to either category be allowed to participate at all? Eurabia and Jew York City are, at their roots, concepts which demand the ghettoization of the groups from which they take their names, their exclusion from any non-subordinate role. These terms' use is a good marker for some sort of highly exclusionary racism.
Moral argument aside, the demographic argument is nicely skewered by Randymac earlier in the post and then finished off by Zachary Latif in the comments:
Cognitive bias skews perception and Randy makes the very good point, that all things being equal, a population of 15mn isn't exactly going to overwhelm 480mn in the forseeable future. As for forecasting to 2100, it's futurology and in the same manner how my 1970's books commented on the 90's.
The maths don't work and one would have to build certain stereotypes to conclude that it could ever happen; i.e Muslims inherently have large families and part of their cultural self-awareness.
Well Iran, the Islamic theocracy, has a plunging TFR (total fertility rate) as Iranian women are encouraged, by Mullahs no less, to use contraception and limit their family size. Surely there is some truth in that Dutch Muslims would have interact in a more liberal environment than their Iranian co-religionists?
Some time ago, Randy had made a more detailed demographic analysis of muslims in France using actual census figures. Also see Scott Martens' comments in followup. The main point is that muslims represent such a tiny minority that any talk of conquest-from-within is fear-mongering driven by anti-muslim hate rather than any legitimate concern about borders, language, and culture.
However, this is not to deny that minority groups can often wield disproportionate political power. My observation, however, is that the political influence they wield is directly proportional to their perceived persecution complex. The perception of persecution (whether valid or not) is the single greatest impetus towards political activity.
The Jewish community has been historically active, politically speaking, because their history of persecution is tragically well-documented. The ADL serves an essential watchguard role. On the foreign policy front, the AIPAC lobby derives most of its urgenyc of action from the perceived existential threat to Isreal's existence (a threat which, unlike the domestic case, is now largely moot in my opinion given Israel's complete air and ground superiority).
Note that the importance of CAIR, and the increased political posture of Muslim-Americans, has also grown in direct response to 9-11 and the infringement of civil liberties. I believe that the political influence that the Euro-muslim community wields will follow similar lines, especcially if the reactionaries continue to overstep their bounds with regard to demanding cultural assimilation at the expense of religious freedom - such as coercing muslim schoolchildren to eat pork meals at school with the threat of expulsion (original article in french).
It is the right of the Jewish community in America and the muslim communities in America and Europe to press via the political system for their rights. What is not right is participation in that system as a means to dismantle it, of course, but anyone who claims that the mainstream muslim community on either side of the Atlantic truly seeks an overthrow of civil law and institutionalism of extremist Shari'a has a substantial burden of proof. Ultimately, the muslim and jewish communities will find it impossible to prevent significant cultural cross-pollination as their numbers grow (as can already be seen in the high rate of crossover marriages in the Jewish community here in the US). So by the time muslims reach numerical mass significant enough to pose a potential threat to the established order, if ever, the question will be largely moot. Only racists can argue otherwise.
 I think that the actual influence over foreign policy is not as great as AIPAC imagines. There is a considerable influence over foreign policy by the neocon cabal, but that derives from their fundamentally Cold War mindset of proxy nations. The entire Iraq adventure is to create another Israel, a proxy nation for regional influence.