Mickey Mouse is still outside of public domain. I don't see current corporations allow the major characters to go public domain. There will no doubt be another "Sonny Bono act".

from Wikipedia:
The Sonny Bono Copyright Term Extension Act – also known as the Copyright Term Extension Act, Sonny Bono Act, or (derisively) the Mickey Mouse Protection Act – extended copyright terms in the United States in 1998. It is one of several acts extending the terms of copyrights.