Towerjazz: It must not be easy for Nikon and others to solely rely on Sony sensors when Sony also has their own cameras
In this interview with TowerJazz posted by Charbax you can find some interesting info:
Minute 7: He confirms that some Panasonic cameras use TowerJazz sensors
Minute 8: He sees a problem in the fact that Sony is also a camera market. So for example if there is competition on the supply Sony may give themselves the benefit instead of Nikon.
Minute 12:40: He says 8K and speed are definitely coming but the rela challenge is advancaments in High Dynamic Range.