Looking at the cutouts, there is one at the top left corner in the photo which is presumably for the camera and the flash unit. There is another long cutout next to it which would be for the volume rockers, and another cutout at the top middle which most likely is where the Smart Connector will be placed.
Then towards the right middle portion, you’ll notice a pill-shaped cutout which is what is leaving many puzzled. Now this isn’t the first time that we’ve seen this. As MacRumors points out, a report from back in July, a CAD image shared by developer Steve Hemmerstoffer revealed a mysterious feature on the back of the iPad.
It has been suggested that this could be where the Smart Connector is being relocated, but that doesn’t make sense since it means that the iPad Pro can no longer be connected to the Smart Keyboard and used in horizontal orientation. However at the very least the rumors are consistent, but until we get the official details it’s probably best to take it with a grain of salt for now.