Although Wayne passed away in 2009, his voice was used for Mickey in several projects that were released after his death. This is because of the way voice acting works; recordings are often made in advance and then used for later projects.
For example, Allwine voiced Mickey in the 2010 video game "Epic Mickey," which was released after his passing.
It's important to note that this is a bit of a complex situation. While Allwine is considered the definitive voice of Mickey, there have been several other actors who have voiced the character over the years.