I think it's part of the plan:
Have whites speckled across the globe, in non-native lands, reproducing with non-whites. Thus reducing the white population further.
This is something that projections of demographic decline don't take into account: the snowball effect as white Europeans who have the opportunity to leave, do so. The big question, though, is the question posed by Houellebecq in Submission when he says, "Europeans have no Israel": Ultimately, there is nowhere for us to go outside Europe.