What We Expect

We don't expect to see the iPhone 7 until the fall of 2016, so it's quite a ways off. Apple just released their 2015 models, the iPhone 6s and the iPhone 6s Plus.
Apple has used an alternating "S" naming formula to mark years where the iPhone does not receive a major redesign since the debut of the iPhone 3GS in 2009. Releases have been as follows:
2007 - iPhone
2008 - iPhone 3G
2009 - iPhone 3GS
2010 - iPhone 4 (new design)
2011 - iPhone 4s
2012 - iPhone 5 (new design)
2013 - iPhone 5s
2014 - iPhone 6 and iPhone 6 Plus (new design)
2015 - iPhone 6s and iPhone 6s Plus
The next iPhone is expected to be called the iPhone 7. 2015 marked an "S" iPhone upgrade year that introduced new features such as an improved camera and a better processor, but 2016 will bring an even-year upgrade that will likely include an all-new iPhone design.







Apple's 2014 iPhone redesign brought the iPhone 6 and the iPhone 6 Plus
We are too far away from the iPhone 7 launch to know what the new device will look like, but we can speculate that Apple will continue on its path of introducing more powerful, efficient devices that grow thinner with each design iteration.