Epic Mickey 3 is an expected video game in the also expected Epic Mickey trilogy.
Announcement: Warren Spector was asked about creating a trilogy. He said that was what he had in mind. These are some of Warren's exact words: "I don't do anything that isn't extensible. And I will certainly feel that I have not done my job if we can't make other games in this world with these characters. In my head, I've got two more planned."
Warren Spector also says that just because someone plans a trilogy, doesn't mean it will happen in reality. Spector has also confirmed that he has an "idea" for the story of Epic Mickey 3. Spector has stated that the musical bits of Epic Mickey 2: The Power of Two are a "test bed". And that for the next game he will be going crazy with the musical songs. Depending on the timing the next game could see a potential release on the Next Gen platforms.
On January 29th, Junction Point announced that it's closing and Epic Mickey 3 will not happen.
Epic Mickey 2 Teaser: A brief teaser was shown at the end of Epic Mickey 2 that shows all the Petes going to Ventureland saying: "Look at them all, so happy. They ain't even going to know what hit'em!". This showed the possibility of the Petes being the villians of Epic Mickey 3.