I believe James Earl Jones headed an all-black cast of The Cherry Orchard for Joe Papp back in the 70s. The reviews for the production were good.
I see no reason why an all-black cast would not work for any number of plays with no script changes. I do wonder about the plays of Tennessee Williams which are often Southern-specific and time period specific.
Big Daddy in Cat is a wealthy landowner in Mississippi in the 1950s. How did he get this land and more importantly givern the time and place, how was he allowed to keep it?
Streetcar works a bit better, but still someone had to get the land that Blanche has lost. In postwar 1940s (and really post WWI) Louisiana that really wouldn't have happened. The family, even if they owned the land in the first place, would have lost it by force if necessary, a long time ago.
However my biggest problem here is these two stars. I don't think the Smiths have the chops for Stanley and Blanche. He has no danger and she has no vulnerability.
Long Day's Journey would sort of work, but bear in mind that the time period would make James Tyrone, Sr. a star on the chitlin circuit, not the main theatres in North America. I think James Earl Jones did play James Tyrone somewhere, but I wouldn't bet on it.
All of these plays are about the family dynamic and not about being Black in America.
"If my life weren't funny, it would just be true. And that would be unacceptable."
--Carrie Fisher