I have not heard any announcements yet about wifi calling here in Canada. Has anyone heard anything yet.
It seems that it's already possibly available here with some providers, and providing one has a compatible phone, so says some hits with a Google search:
We’ll support the iOS 8 Wi-Fi calling feature when it becomes available in Canada. In the meantime, Rogers customers using the Rogers One Number service on their computer, tablet or smartphone can already make calls over Wi-Fi. They can video chat with other Rogers One Number users or call any Canadian number for free, no matter where they are. For more info on Rogers One Number http://Rogers.com/OneNumber.