When whites have it tough, too
The biggest blow to affirmative action in its nearly 50 years of existence was the election of Barack Obama to the presidency of the United States. Not because Obama is against the policy (he is, as on so many issues, nuanced in his support; i.e., he believes it should exist but not extend to his children) but because his election was widely perceived as being reflective of a profound shift in the country's racial balance.
I believe that white racial anxiety, not immigration, will be the most significant and potentially dangerous socio-demographic trend of the coming decade. The combination of changing demographics and symbolic political victories on the part of nonwhites will inspire in whites a greater racial consciousness, a growing sense of beleagurement and louder calls to end affirmative action or to be included in it.