Earlier quoted context omitted.
I'm talking about a world where the character is a trademark, a distinctive brand in and of itself and where the "creator" is no longer a living person, but a corporation that continues to create work with the characters. Steamboat Willy is a distinct piece of art. However, the characters in it have become brands unto themselves. The world of trademark and copyright are colliding in a new way here if Steamboat Willy…
The relevant case here is a recent decision regarding the Sherlock Holmes books published before 1923. The characters represented in those works (i.e. without later developments in still-copyrighted books) are in the public domain, and can be freely used in new stories. There's no reason to think that the same wouldn't apply to Micky and Donald. http://artsbeat.blogs.nytimes.com/2013/12/27/sherlock-holmes...
How many remakes of Shakespeare, Jane Austen, heck, stories from Greek mythology and the Bible have been made? Lots.
As many have noted (including someone upthread), Disney itself strip-mined the public domain for many of its big-budget pictures.