Nothing in that says Disney can block producing derivative works based on works in the public domain. It's simply stating that Mickey Mouse can be a trademark a

Nothing in that says Disney can block producing derivative works based on works in the public domain. It's simply stating that Mickey Mouse can be a trademark and trademarks can last forever. But trademarks are also subject to fair use, for example when factually describing a product. So a Steamboat Willie YouTube video would be either redistributing a public domain work or it would be a derivative work. And calling it "Steamboat Willie" would be descriptive. I think Disney would have an uphill battle to stamp out all uses of Steamboat Willie. Though they certainly have the money to do so regardless of what the law seems to indicate.