If I understand it correctly, the version entering the public domain would also include the author's own editions (as the limit to copyright of an author is 70 years). In Dahl's case, he had removed some elements that were offensive already in the 60s-70s - think Oompa Loompas as slaves from Africa paid in cocoa beans in his first version. So you would have the still colorful and probably somewhat controversial author versions go into the public domain, and the sanitized versions remain on the publisher side if authored by someone else with new copyright running etc. I agree with the prediction that both types of versions would probably find an audience, and would also predict that kids would probably gravitate towards the version that is the most lively and colourful.