According to code discovered within the iOS 7 SDK by a developer, the next iPad mini will not have Retina display, but be powered by the A6 chip currently found in the iPhone 5, reports 9to5Mac:
From the references, we can also infer that this potential iPad mini model will lack a Retina display. The versions of these references for Apple’s Retina display devices, such as the iPhone 5 and fourth-generation iPad, include hooks to images at a “@2x” mode. “@2x” is how developers reference app artwork that is built for a Retina display device. However, these new iPad minis lack the “@2x” hook, including only references to non-Retina images. Perhaps corroborating this is that the rumored Retina display iPad mini codename is “J85,” while the iPad mini model we have learned about is “J75.”
New iPad models “2,8,”, “2,9” and “2,10” were found with codenames being J75, J76 and J77. Reference to “s5l8950x” was also discovered, which refers to the A6 found in the iPhone 5. Based on what the developer was able to dig out from the iOS 7 SDK, one can allude to features coming in upcoming iPad mini models. But of course, just because they were found does not mean Apple will release these models at all.
A recent report by hit or miss publication Digitimes noted the iPad mini would possibly ship with a Retina display in October, based on whispers within Apple’s supply chain–despite contradicting its own earlier report models would not come with the higher resolution display.