It looks like Retina display is something the next iPad mini won't get. A Taiwanese publication reported that Apple is having trouble achieving Retina-like pixel-densities (over 250 ppi) on displays in a 7.9-inch format. The trouble here is getting acceptable yields on these displays, and Apple doesn't hope to iron these issues out in time to get these displays manufactured in good enough volumes.
The report states that it could be early 2014 by the time Apple is able to source 7.9-inch Retina display panels, and it's only then that we can expect iPad mini with Retina displays to come out. In the mean time, Apple could attempt to roll out a 2nd generation iPad mini anyway, with slightly higher resolution than the 1024 x 768 pixels the original ships with, which could make the oh-so-coloful iOS 7 come to life.