AFAIK, the part that's been debunked is that there's a complete separation of concerns between the two hemispheres. From studies on split-brain patients, there does appear to be some specialization, but it's much fuzzier than "right brain does art, left brain does analysis" or anything like that.
Only when it comes to "left/right side analytical/creative" split, and even that mainly based in a single 2013 study, which could have all kinds of issues. Not regarding different functions in general.
Also, I think you are talking about the corpus callosum for the 'bus' right?