I do not know that assimilation for today's immigrants to western countries is possible. But I will say that assimilation is a bare minimum requirement for any immigrant coming to the US or any other western country. By moving here, you are admitting that we are doing something better than your country of origin. And if we are not, then why are you here instead of there?
Being here for economic reasons alone shows you are not assimilating, and you therefore should not be here.
On this topic, I see why libertarians have no issue with immigrants solely here for economic reasons. Because they seem to only view countries as economic zones themselves, so they see no issue with immigrants viewing the country as that same way. But they fail to realize that immigrants don't share the same view on general freedom that they do. They simply demand more laws and policies in their favor while seeking the most economic advantage they can.
@houseoftolstoy and then you can open the borders to productive people.