Since many depictions of Mickey are registered as various trademarks of the Disney conglomerate, things will basically shift from copyright to trademark law and

Since many depictions of Mickey are registered as various trademarks of the Disney conglomerate, things will basically shift from copyright to trademark law and they will be less able to say “you shall not pass” but they can definitely still make your life hell if you cross them. Edit: I forgot to mention that I suspect that Disney started using their new pre-movie intro motion graphics that are heavily derived from steamboat willie as a bit of a hedge, since they get a reasonably strong defence from the complete inclusion of the opening sequence of steamboat willie against potentially confusing trademark infringement. It’s also a sneaky way to get a new copyright covered variant of their original material.