I don’t think it’s referring to immigration but rather the economic success associated with the American Dream- owning a house, a car and having a plan for retirement.
What a perfect society looks like is of course an incredibly hard question to answer. But not knowing the exact ideals does not discount our ability to recognize a bad state. We can move in a better direction, and yes, it's possible that we make a mistake in the other direction. But the chances of that happening are so laughable as to not even consider it.