The problem is apparently related to Sharp's TFT technology and has resulted in low production yields for the display. LG Display, Apple's other main supplier of panels for the product, has not suffered from the same problem. There is speculation that Apple will turn to its rival and supplier Samsung, to provide the panels necessary to finally launch the slate. The Korean based OEM previously solved a burn-in problem with the Retina display panels produced for the full sized Apple iPad.
Considering that not one Apple iPad mini with Retina display has been shipped, the demand for the tablet is bound to be extremely high when it is finally launched.
source: ETNews (translated) via BGR