Every few years we hear discussion about Canon and medium format, as noted by Northlight Images, it usually happens in a Photokina year, which 2016 is. With rumors of Sony and Fuji entering the segment, the talk of what Canon's plans are have come up again.
For the moment, Canon is paying attention to the medium format market, but have no currently plans or team in place to develop such a product. Canon has in the past made medium format sensors that top 250mp, but those were engineering samples.
Northlight notes that the “official” line from Canon is that there is lots of development possibilities with 35mm sensors. Not to mention, that the medium format segment likely wouldn't be profitable.
We know that Canon has looked into medium format acquisitions as well as development, but it doesn't look like we're going to see them go beyond just tinkering.