Keep in mind, a copyright is on a 'work'. In other words having a copyright on a film cartoon basically means that the entity that created the cartoon chooses how the cartoon will be used, sold, distributed etc. It also covers any unique characters in the cartoon as well, Example: Jerry is a mouse and Mickey is a mouse, but their unique appearances are protected by copyright(yYou can't copyright 'mouse').
When the copyright for a particular cartoon expires, anyone can reproduce, distribute, etc the cartoon AND can do what they want with any unique characters as well which would include 1928 Mickey!!
But wait - Disney has Trademarked all the various versions of Mickey (and I imagine most of their characters). Trademark is very different. Trademarks for example, never expire.
So while it might be possible at some point to buy a copy of a 1928 Mickey cartoon without Disney controlling it, until Disney Inc. goes out of business they will continue to be the only company making coats, cartoons, dishes, etc using a 1928 image of Mickey (or any of their trademarked characters).