The oleophobic coating on the display has been a staple of the iPhone since it first appeared on the 3Gs. So, it's not much of a surprise that Apple would want to keep that streak going. And, if Apple is going to stop using Gorilla Glass in favor of sapphire glass, it seems that the method of adding that coating will have to change. The theory is that because sapphire glass has a crystal structure, the coating can't bond in the same way.
Of course, Apple has sorted out how that coating can be applied, and with that discovery, filed for a patent on the process in September of last year. The patent was granted today by the USPTO, which would give Apple plenty of time to use sapphire glass in its next set of iPhones.