Dude, let's not be silly. I wholeheartedly doubt that "black people" are afraid of a "mulatto uprising." I think "black people" are more afraid if not most afraid of not progressing due to perceived racism (real or not) by whites who have the real power. Besides, there have been plenty of "mulatto" (those people who phenotypically have kind of a beige skin color, and caucasian features) "uprisings" against darker skinned people be they in North Africa or Western USA or South America. Actually, these people whether they be mestizos, mulattos, dark caucasians are already racist towards darker skinned people, which most of the time includes Black people and native Indians - ie, the systemic racism is already there. There isn't going to be some sort of "big bang uprising" wherein "mulattos" start to "uprise" against darker skinned people or "black people."  The concept of "black" and "mulatto" aren't diametrically oppossed like the concepts of "black" and "white." The worst thing that can happen is balkanization.  Furthermore, as white people continue to identify as "white", I don't see the idea of "blackness" going anywhere soon.