I was just thinking about this. It's definitely possible when you consider: The iPad Air 2's processor is Tri-Core and the battery life is still the same as the Air's despite the battery being 1500maH smaller. The iPhone might stay dual core and have even more efficiency. The iPhone 6s will be thicker than the old phone. More volume for a larger battery. Better battery life is a major focus in iOS 9. Maybe the iPhone 6s will have further optimizations for low power mode that require hardware. Honestly, this would be a feature that would make it certain that I would upgrade. Do you think it's possible or likely?