I would imagine joint ventures on something as expensive as sensor manufacturing would help lower costs for companies and perhaps customers as well. It’s definitely possible, but I wouldn’t write it in stone yet. If Canon does the manufacturing of the sensor can they put their own technology into a Sony sensor, such as Dual Pixel AF?
In other industries (cars etc.) it is frequent to see exchanges of know-how.
Maybe it could be possible for Canon to supply DPAF technology and for Sony to supply DR in the same sensor.
BTW, 46 Mpx is exactly what I need to replace my 5d classic: shooting in S-RAW, I expect to get excellent noise-free 11.5 Mpx pictures.