Traditionally, for several years, the iPhone has followed a two-year evolution cycle with a major evolution followed a year later by a minor evolution taking up the design of the previous model. After the iPhone 6 and iPhone 6 Plus in 2014, it would therefore be logical to expect iPhone 6S and 6S Plus, maybe counting a iPhone 6C.
However, the arrival of the system Force Touch, which will distinguish several levels of pressure and will first be offered on the Watch and the MacBook Retina (in the trackpad) before likely ending up in the next iPhone, could constitute an advance such that the future model could directly become an iPhone 7 rather than an iPhone 6S.
At least that's what the analyst suggests Ming-chi Kuo of KGI Securities indicating that this characteristic is likely to deeply transform the iOS interface.
He also suggests that the technology in question does not directly measure the pressure exerted but rather works by determining the contact surface finger and extrapolating the pressure exerted on the slab.
This would in particular allow keep the finesse mobile devices and continue to use in-cell LCD panels. For the analyst, the iPhone 7 and 7 Plus will keep the same screen diagonals of 4.7 inches and 5.5 inches.
On the other hand, the analyst is rather circumspect as to the existence of a iPhone 6C with a 4 inch screen that forces the rumor of a iPhone low cost which is however not in the spirit of the group's product ranges.