I have been following the iPhone 7 rumors and so far it looks like the changes may be minimal. At least it seems to be that way to me. Everyone expects software updates, etc. It looks like there will be a change to the camera on the iP 7 Plus. Still I have not heard of anything that I would shout about.
Maybe there is one thing to shout about, and when I say shout, I don't mean "YES!", but rather, "NO!". It looks like Apple has decided to remove the 3.5mm headphone jack. If you want to listen to... ...well... ...whatever, you will have jack into the Lightning port. Yes!!! Another adapter to purchase. Apple will provide EarPods with a Lightning connector.
There are other improvements that look like may be here late 2017 or 2018. These changes would mark true update stature in my book.
The Home button may go away. Just touching the display would unlock your phone. They are calling it TTDI (touch and display driver integration)
Long-range wireless charging, which does not require devices to be as close to a charging source or mat.
5.8-inch display that will wrap to the sides of the phone for better alerting and possibly adding gestures.
It looks like Apple is moving away from the all aluminum body and going back to the glass back like in the iP 4 and 4S. This would help with biometric recognition as well.
It is also rumored that Apple may be looking at a curved phone in the next year or so and in 2017 may skip the "S" upgrade and jumping right to the iPhone 8.
We will see.