Generalizations are how we function in a complex and multicultural society. Average IQs tend to be an indicator of a general population. I don't think individual cases and outliers should be used to assess general trends- sure there are probably lots of freedom loving liberal Syrians or Somalians, doesn't mean I want to live in a neighborhood full of them or that I want my kids near the offspring of these traumatized families. I think focusing on the brilliant (potential) individuals runs dangerously close to a strawman argument. I'm not as positive as you about the future, but I do not think the sky will fall either.
To be frank, the only thing that bothers me is the cultural clash and the inevitable raising of my already exorbitant taxes. Beyond that, it's not like I will be living in those neighborhoods (for now, back in London it's another case entirely) or that they will be competing for my job. I think it's somewhat humane what Germany are doing but far less altruistic than they claim (birthrates and all that).
Yet again let me bring you the Pareto principle. The 80% of the general population will never manage to fast forward our society because they simply can't. The ones who do are almost every time the other 20%. To be specific, the 20% of the 20% are the unique geniuses among the general population who "are crazy enough to change the world".
Being "afraid" of the aliens, or don't want them anywhere near us, pretty much certifies the disability of our society to form a global community where everybody is equal to one another. All social schemes have previously failed because of this myopic visualization and incertitude of our "egotistical self" against the "low-end neighbor" (who might prove himself better than us).
It's the NIMBY (Not In My Back Yard) motto that we used to have when we first started to get our rubbish sorted out. Only this time we present it with other human beings... Yeah. Shit.