In the run-up to the iPhone 6 announcement, the rumor-mill had basically decided that we were getting a strengthened sapphire screen — something that ultimately proved to be completely false. TIME has an excellent breakdown of why Apple didn't go the sapphire path.
According to the author, the likely reason that Apple didn't go for sapphire wasn't the rumored supply issues — rather, sapphire doesn't really make sense for a phone screen. There are the obvious issues, like the added cost of sapphire over Gorilla Glass; but there's a myriad of less-evident reasons, like the battery life issues sapphire would incur. Most surprisingly, sapphire apparently isn't any better in a drop-test scenario — the added rigidity means the sapphire is more liable to crack than glass, which bends to absorb the impact.
The full piece is worth a read in detail — but basically, there's no end in sight for the millions of people suffering from Cracked-iPhone-itis. [TIME]