The Steamboat Willie version of Mickey Mouse is in the public domain, and you can create and sell your own works using this version of Mickey Mouse. But you'll get lawyers on your tail if you try and use ANY version of Mickey Mouse as a trademark to sell a product. As long as Disney follows the law in keeping the name and image of Mickey Mouse alive as a trademark, nobody else can use it
as a trademark, in perpetuity. But as time goes on, various other renditions of Mickey Mouse will continue to enter the public domain and be available for use in creative works. You can't stop someone from using a trademark in a creative work, unless it's to explicitly sell the product as a brand.
The personal rights of people vary by state. In California, they are retained by the deceased person's estate or heirs for 70 years.
California Celebrities Rights Act - Wikipedia
Now, if a celebrity (notable examples include Elvis, Billy Idol, and Billy Joel) trademarked their name, those IP rights can theoretically be maintained in perpetuity. Elvis Presley Enterprises (EPE) can keep the Elvis name protected as a trademark in perpetuity, along with the TCB lightning bolt, etc.