Image
Based on the shadow cast by the leaked display in the 3rd photo of the OP, it looks to me like this part is thicker than any existing apple notebook display.
My guess is that apple may have trimmed the logic board right down and is now housing it between the display assembly and aluminum case; which would justify the removal of a backlit apple logo, and also a reduction in heat that the battery is exposed to, making it fanless.
That leaves a couple of ribbon cables for a usb port, 3.5mm headphone jack, and keyboard/trackpad and battery for the bottom sub-assembly.
I'd be dubious as to the reduction in overall thickness, but rather a compromise to maintain battery life with a more power hungry retina display.