Wait, does the copyright not just cover the actual movie/videos/art/... of that time, still having them own the character itself (since they're actively using it)?
I believe that officially only the movies, etc., would fall into the public domain. But people can make derivative works of public domain items, so they wouldn’t be limited to literal copies of Steamboat Willie. They could show Steamboat Willie using a smartphone.
However, Disney also has trademarks on Mickey Mouse, etc., so using Mickey’s likeness in commercial ways would still be a legal minefield.
However, Disney also has trademarks on Mickey Mouse, etc., so using Mickey’s likeness in commercial ways would still be a legal minefield.