mowibble, although i generally agree with everything you stated - it is a curious fact that the dilution you refered to is for some reason not happening in muslim communities. its the reverse in fact. i read some literature regarding this but sorry dont have the references right now.
it is true that this may be a post 9/11 effect, may be temporary, may be confined to certain western nations due to ghetto-isation.... whatever. point is the expected dilution we observe in people from other cultures is not being reflected in islamic cultures...
we dont see people with thick accents protesting the loudest... its thick aussie accents, locally educated, born in Oz type of folks who are doing the protesting.
in most other cultures that migrate to western lands, there is a cringe factor in the 2nd/3rd generation and the kids tend to assimilate/westernize to be cool. not sure why this is not happening to a greater extent in the muslim community? infact, showing your muslim-ness is a badge of honour for some young muslims. its a curious trend.