Next iPhone to sport a touch-enabled home key out of sapphire, doubling as a fingerprint scanner70
Sapphire, besides the name of a Las Vegas strip club, is a durable organic material that is times stronger than Gorilla Glass, and the only reason manufacturers haven't gotten all over it for smartphone and tablet displays is that it is expensive and can't reach yields suitable for mass production of such panels just yet.
A home button piece is an entirely different story, though, and since Apple already has experience with sapphire material, it isn't that far fetched of a rumor that it might be used more extensively in the next iPhone, be it only to set it apart.
The home button is said to be of the capacitive touch variety this time, not a physical key prone to breaking with prolonged usage. After all, the handset is heavily rumored to have a fingerprint sensor integrated there, so that might be one of the reasons for Apple to go with a sapphire layer.