Canon has applied for a patent on another highly detailed stacked sensor.
This patent application is for suppressing the dark current and/or leakage current by using diffusion preventing films surrounding the bonding areas.
This is a very highly detailed patent application, going into a significant amount of diagrams and specifics. It stands to reason that Canon is heavily investing it's time in and energy into stacked sensors, and these patents seem to indicate just that.
Of course, with all patent applications, this is research that Canon is doing, whether or not it ends up in an actual camera is yet to be seen.
US Patent Application 2018-0166494