I am crazy excited for this production and can't wait to hear Josh Henry and Jessie Mueller sing the score!
As far as the racial dynamic, I think it's going to make for a very thought-provoking, perhaps ambiguous, production. I haven't thought about the domestic abuse, but I was listening to the album the other day, and the beginning of "If I Loved You" really struck me. Billy says something along the lines of, "Ain't you scared of me? Especially after what the cop said about me stealing?" And Julie says something to the effect of, "No, I didn't think nothing about what he said."
That exchange caught me in the context of thinking about this future revival. Billy's reputation will certainly be raced, and Julie's reaction will allow thinking about racial prejudice.
Re: casting a person of color as Julie, I saw an excellent production at the Stratford Festival in Canada in 2015, and Alexis Gordon (a black actress) played Julie opposite a white actor as Billy. I and don't remember being struck by any particular racialized dynamic as accentuated by the text.