According to Canon Rumors 2016 will be the year that Canon will focus on an updated mirrorless system.

“We’re told Canon is actively developing EOS M and EF-M products and 2016 will be the year they “get serious about the platform”. Multiple zoom and prime lenses are in the late state of development and announcements should begin in the first part of 2016.

We’re also told that an EOS M4 will be a global product and a departure from what we’ve seen through the first 3 iterations. There was no information on sensor size, but I suspect APS-C will remain part of the system.
It would be a great if Canon put real resources into developing the EOS M system.