As much as Apple fans would love to see an iPhone 6 with a sapphire screen, an iWatch (also with a Sapphire screen), an Apple TV, and Touch ID in new iPad Airs and iPad minis, we may not get everything we wish for. While there has been a lot of buzz regarding those sapphire screens, which should prove harder to scratch, they may not be ready for a September announcement.
The latest rumors show that those screens may not be ready until later in the year. It's always hard to create a new product that depends on new technologies, and Apple typically waits until the product is ready. In fact, Steve Jobs cried when he learned the original iMac would have to ship with a caddy-based CD-ROM instead of a sleek slot-loading drive as he envisioned.
However, the annual lifecycle of smartphones dictates that Apple can't delay a September announcement. Wall Street expects an announcement, and users who bought the iPhone 5 two years ago are coming off contract. When I worked at Sun Microsystems, we had this concept of a train leaving the station. We shipped whatever features were ready by the time the train was going to leave, and the other features would get in the next release, six months later. It made it easier for businesses, and developers, to plan for.
So, if Apple's sapphire screens aren't ready for September, when the rumored 4.6-inch iPhone 6 should come out, then maybe the 5.5-inch version will get the new screen. And since the rumored iWatch isn't replacing anything in Apple's product line, they can wait until it's ready.