We're told by a pretty good source that any announcement in regards to a medium format entry by Canon is a “longshot at best”. While Canon is always doing R&D on the concept, there is “nothing that is imminent”.
Another source has told us that these rumors could have “some truth to them”, but wouldn't be shown until the Canon Expo in 2015. Canon does a technology expo every 5 years, and tend to show a lot of technologies that may or may not ever end up as a consumer product.
I'm of the belief that medium format at this time wouldn't make much sense, especially since Canon still doesn't have a high resolution 35mm DSLR.