So if it isn't clear, I'm siding with the speculation and rumors that favor the 1024×768 screen on the iPad mini. That is completely in line with the graphics capabilities present in the chip that was optimized for the iPad 2 and famously underwent a critical die-shrink, lowering costs and improving power efficiency.
I think that Apple hasn't completely solved how to drive a 2048×1536 iPad display cheaply and compactly. The new A6 processor has the raw oomph of the 3rd generation iPad, however, as expressed in the iPhone 5, it lacks the memory bandwidth to support a retina-class iPad display optimally.