It's not often Playbill brings you something that's, well, intriguing and interesting, but this story is. Casting updates are rarely actually "news;" we all know that they're essentially (if not actually) just published press releases. But this one...I think, is. And should be.
Having an African-American actress play this part is actually a major shift in that play. Ms. Rashad is quite light-skinned, but she can't really pass. So the question becomes...since it's about a family...what happens with the rest of the cast?
I just saw it, with Estelle Parsons, and I was somewhat surprised to find that it's a great play. I knew it was a great production, but in the play itself, I found a depth I hadn't heard hinted about. With Pulitzer Prize-winners, the tendency is to pick a play that makes rich white people feel comfortable. Whether it's a safe exploration of a subculture, a serious meditation on the effects of white people on a minority, or, more often than not, a play about the very serious problems of rich white people. I'm not faulting all of these as plays, or saying they're not good, but they live within a very narrow wavelength.
August: Osage County starts off very much about the problems of rich white people, but near the end, it gains a resonance about the generation raised during the (first) Great Depression and how that experience changed them and affects their families and, by extension, the country. It's not too heavy-handed, but it's there and it's effective (more effective than the standard, minority-outsider-observer). I can definitely see why it won the big prize.
But if you change the racial mix of the play...woo, boy. I think you wind up with something even more interesting and complicated. Not to mention making the whole family biracial...it would be absolutely worth seeing again.