The rumour mill is really heating up, and there have been quite a few leaks showing a larger iPhone. Healthkit is also getting more features in the new betas, including built in support for step counting.
What will be more interesting this time will be what Apple does with the internals, particularly the SoC and camera. On the SoC front, we’ve been stuck on the 28nm node for almost a couple of years, and they’ve already played the 64-bit card to improve performance last year. Maybe they’ll astound everyone by announcing that the new SoC (A8?) is fabricated on Intel’s facilities on their next-gen 14nm process. In fact, even using Intel’s mature 22nm process would be pretty revolutionary. There have been regular rumours of such partnerships over the last few years, so maybe this is the year of the switch?
On the camera front, the decreasing thickness of the iPhones will surely limit the sensor size & optics. The 5s was probably the limit for the 8MP sensor size. This is going to be a really interesting area as Apple has thus far never traded off device aesthetics for camera specs.