The mockup picture above shows the 4G (perhaps 3rd generation) design as can be seen through the black bar. It also includes a digital camera... however because it is a mockup, anything more might have been added. There has been whispers about the digital camera becoming dropped even though an iPad small having a rear camera can make much more feeling than the usual bigger iPad with a back camera... I have probably only used the actual iPad back camera once or twice and also the reason for that was when Photobooth was made accessible and I wanted to see what it might do.
Additionally, exploring the rear from the casing you can see across the bottom edge a smaller dock connector. This was added due to whispers of the more compact pier connection replacing the regular thirty pin number design that we have experienced for about a decade right now.
Anyhow, I thought it would be fun to just publish the image so you can image resolution what an iPad small "may" look like when and when this ever commences.