Apple currently uses Apple A6 and Apple A6X processors in the iPhone 5 and iPad 4 respectively, and if a report today is accurate, they'll be continuing to increment that series of systems-on-a-chip (SoC) through 2015, when Samsung has reportedly signed on to begging fabbing Apple A9 SOCs on a 14nm process. According to the Korea Economic Daily:
According to industry sources on July 14, Samsung Electronics signed an agreement with Apple to supply the next-generation AP that it will produce in 2015. The AP that will be produced using 14 nano FinFET technology is mounted on Apple's iPhone 7 to be released in the second half of 2015.
While Apple is rumored to have switching away from Samsung to TSMC for the next couple of generations of A series chips, Samsung getting to 14nm first is what's apparently bringing Apple back. Which means, if this report is to be believed, performance trumps patent disputes. (Or, at least, while Tim Cook has said a lot about protecting Apple's IP, he doesn't seem to take it as personally as Steve Jobs did.)
Smaller fabs typically result in smaller, less power-hungry chipsets, which translates into better battery life for devices. I've heard the Apple A7, or whatever the next A-series chip is called, will be "more advanced", but that can be interpreted in many different ways. Given the direction Apple went with this year's MacBook Airs, however, and the need to eventually reduce the size of future iPads, and increase the screen density of future iPad minis, battery life certainly isn't getting any less important.
As to throwing around the iPhone 7 term, it's probably just a handy placeholder reference for whatever high-end phone or phones Apple will almost certainly continue to release into 2015 and beyond. Sticking to the current pattern, 2013 will be an iPhone 5s, 2014 would be an iPhone 6, and 2015 would be an iPhone 6S, putting an iPhone 7 in line for 2016. Apple doesn't always stick to patterns, however, and certainly don't decide on names years in advanced (or even weeks in advance).
So, in other words, take all this will 14nm grains of salt...
Source: Korea Economic Daily