I had a really long convoluted discussion with an IP lawyer, and he claimed that only specific instances of Mickey Mouse's likeness were protected by trademark.
I haven't really absorbed his argument, but he seemed pretty sure about it, and that we needed something else to (legitimately, in both our opinions) protect Disney's ability to control their brand even if copyright expired. He recommended giving Disney something very much like "right of publicity" for Mickey Mouse so they can still control the character, while allowing lots of old stuff to still enter the public domain.
To me, this sort of stuff seems like the IP law equivalent of bailing out banks (or GM) because they are "too big to fail."
Even if specific instances of Mickey Mouse's likeness are trademarked, I have a hard time believing that someone could be selling "Mickey Mouse" t-shirts on the street and not be in a risky legal grey zone.
[I'll also note that as an IP lawyer he probably has a rather conservative view of this. Thinking from Disney's perspective they don't want any trademark lawsuit to be in a legal grey zone. They want them all to be slam-dunks so that they can get their way.]
I haven't really absorbed his argument, but he seemed pretty sure about it, and that we needed something else to (legitimately, in both our opinions) protect Disney's ability to control their brand even if copyright expired. He recommended giving Disney something very much like "right of publicity" for Mickey Mouse so they can still control the character, while allowing lots of old stuff to still enter the public domain.