As an elective, no.
But, if you wanted to make a Shakespeare class mandatory, then, for practicalities of time, the Shakespeare that is taught in English literature would be reduced or even eliminated.
And that is the concern, that if we teach about Harriet Tubman in Black history, that’s likely to reduce the time spent teaching about her in American history.
Once again, I think that the OP comes from good intention, and that intent should be recognized. But the OP’s solution is lacking, and will likely do more harm than good. I’d rather debate the ways of increasing the awareness of the history of Black people and other minorities in the classroom than whether or not the specific proposal of the OP is the way to go, I feel that part is fairly settled.