I'm pretty sure I will upgrade to the iPhone Apple releases this fall. I'm intrigued by the dual camera, and I have a 6s. But I will wait to make the final decision until I see the official details from Apple.
As for the 2017 iPhone, I can say definitively that if I am wowed by Apple's official unveiling of the device, I will definitely consider upgrading sooner than the two-year cycle that I have been on since the iPhone 3G. On the other hand, if Apple reverts to only having one size (3.5 inch) phone and that phone is an 8GB max storage model with 512MB RAM and lacks Bluetooth, I will probably not upgrade early. I'm just putting that out there.
I'm enjoying the rumors about this year's iPhone and next year's iPhone, but any decisions I make based on rumors will be contingent on those rumors being true. If the rumors are wrong then my decisions are automatically void.