I was cast as Radames in our high school production of Aida (i am in the same show as the above commented BrdwyThtr). I think that as long as the vocal demands of the show can be pulled off, the fact that the entire cast is not African-American shouldn't be a problem. I'm sure that there have been several African-Americans who have played white people in shows, and there haven't been uprisings.
Aida doesn't have to be about race. As long as its clear to the audience that Aida and Radames SHOULDN'T be together, it would work fine. Whatever happened to suspension of disbelief?