I really, really hope that they do this eventually. I've always been under the impression that at this point, they would never get the release out.
My wife and I discuss this all the time while we're watching some of our "Classic Mickey" archive DVDs, when anything at all that could be construed inappropriate comes around (stereotypical voicing for the time, protrayals of drunkenness, etc), they just trot out a quick intro clip by Leonard Maltin saying that we know it's not right or appropriate but what was acceptable at the time, the films stand as a piece of history, etc...
My wife thought they would be able to throw out a nice one of those Mea Culpa Leondard Maltin clips and release the Song of the South, trying to diffuse any potential for harm that the original may or may not have. I've always been of the opinion that they would never release it. I thought that the potential money they could make by it's release would be offset by even the chance that someone would become offended or upset and cause a boycott, bad publicity, etc. The potential for loss was most likley greater than the potential money made by releasing a fairly niche film (probably only Disneyphiles would buy it), so it would never be released. I just always thought that given the 24 hour media machine that exists, even if they had a very well worded Mea Culpa video tacked on the beginning, all it takes is someone to show an offensive clip over and over, and taken out of context, this could cause harm that was unintended and cause more loss than Disney would have a potential gain from the release.
Now, all that being said let me say that my memories of the film are very hazy, being that I probably had not seen the film in 25+ years. I do not have the proper context to know if the film could/should be kept on the shelves due to content that may cause harm. I am not an African American, and could never pretend to know if the film is harmless/harmful, so therefore I cannot correctly judge the content/context of this film and if it would even elicit a reaction. If the film truly has offensive content, I cannot remember it, and have little to no place saying if it "should" or "shouldn't" be released. I know I loved it as a child, but seen through a child's eyes, any harmful / offensive content is typically missed.