Nokia 9 is definitely in the phase of a mass production. We can assume that since the photo of the back leaked form the manufacturing plant.
The back case, or plate, is the same as on the Nokibar’s sketch, with curved sides and slightly elevated camera module.
Seems like the camera hump could be back with the latest Nokia flagship. That could also suggest that the camera is more powerful than the one in the Nokia 8, or that the body is thinner.
Also, seems like HMD is changing the design of its phones by pushing the glossy finish. It is definitely too early for any kind of speculation, but looks to me that we could see this device soon. Slush maybe?