As far as I understand (and I'm sure someone will correct me if I'm wrong), iOS does not scale graphics to fit any resolution like Android does. iOS does have a simple scaling function, where it can scale up an iPhone app to an iPad screen, or it can show an app not optimized for retina on a retina display, but this isn't proper variable scaling the way other fragmented OSs do it.
Meaning, developers have to include in their iPad apps the graphics for 1024x768 (to support iPad, iPad2, and iPad Mini) and/or the graphics for 2048x1536 (to support iPad3, iPad4). Unless Apple wants to force develops to support a third resolution, they will probably stick with one of those two for the iPad Mini 2.
For comparison, currently iOS 6 supports 3 iphone resolutions (3.5", 3.5" retina, and 4" retina), but they are phasing out one of them in iOS7 (non-retina 3.5" devices are not supported any more). To me this indicates Apple's desire is to reduce the amount of resolutions developers have to support.