iPhone 6 is the presumptive name for Apple's next-generation iPhone. Yes, it will be the 8th generation phone in Apple's product lineup, internally referred to as iPhone7,1, but don't let those numbers distract you. Apple can call any phone it releases by any marketing name it wants and the next number of 5/5s is 6. So, iPhone 6.
iPhone 6 release date rumors
If Apple holds to previous patterns, the iPhone 6 will be announced on or around September 9, 2014, with a release date of September 19, 2014. That said, Apple doesn't always hold to patterns. There's never been less than 12 months between iPhone releases but there were some 16 months between the iPhone 4 and the iPhone 4s. There were, however, only 6 months between the iPad 3 and iPad 4, so no release date is confirmed until Apple announces an event and tells us what it is.
iPhone 6 screen size speculation
For a long time now rumors have swirled about Apple going to a larger display size for the iPhone 6. The original iPhone had a 3.5-inch 480x320 standard density display. The iPhone 4 took things to 960x640 double-density "Retina" and the iPhone 5 to 4-inches and 1136x640 double-density. That's a pattern of steady improvements every two years on the two years, and if Apple sticks to it, we're due another.
So how big is bigger? Competing phones range from around 4.3- to 4.7- to 5-inches, with the latter size increasingly the norm. Also, how would Apple scale their interface? Would they just stretch the 4-inch iPhone up to 5-inches the way they stretched the iPad's down into the iPad mini? Would they add more pixels like they did for the iPhone 5? And could they increase the screen size without increasing the device size, by going edge-to-edge with the display and modifying the chin and the forehead to once again make something big seem small?
If Apple stays conservative they could scale up the interface this year, add more pixels come iPhone 7 in 2016. If they still have their foot down on the gas, however, maybe we'll see something closer to 1080p HD.
iPhone 6 sensors and specs
Keeping to the pattern theme, ever iPhone announced since the iPhone 4 has had a new, custom chipset announced along with it. That suggests the iPhone 6 should come along with a 64-bit Apple A8 system-on-a-chip (SoC). That would also mean improvements to the iSight camera's image signal processor (ISP) and even better photos.
The M7 motion coprocessor could likewise be updated to M8. Other manufacturers are including natural language and context coprocessors, so there's no telling what else could be done there.
Touch ID is already great from a hardware perspective, but with Apple's PrimSense acquisition, perhaps Kinect-like motion sensing could be integrated into the iSight camera as well.
Speaking of which, Apple has also been working on cameras since the iPhone 4 and if they keep doing that, we should get more with the iPhone 6 as well. Some of that will no doubt be software, things like dynamic focus, but perhaps Apple could squeeze some better hardware in as well, especially optical image stabilization (OIS).
iPhone 6 health and iWatch
In conjunction with iOS 8 and the rumored iWatch, the iPhone 6 could also be part of Apple's next big push — health.