In Stretchy Thumbs, Casey Liss wonders if the new system wide back gesture in iOS 7 (obviating the need to constantly reach to the top left of the screen) is a step towards supporting the idea of a larger screened iPhone Plus. I would say that in most of the new patterns in iOS 7, Apple are telegraphing much more than that: clear steps towards proper resolution independence for iOS.
These changes would pave the way not for an iPhone Plus with bigger pixels, but one with a new screen resolution at current Retina iPhone DPI levels that can display more content on screen. And once resolution independence is established, who knows what other larger or smaller devices it would pave the way for?
The evidence
The first thing to consider is the removal of not just most, but all visual ornamentation. As I noted in my previous post, this is a little bit like the transition from sprite to polygon based videogames. In that world too, moving to polygon based graphics also provided resolution independence.
As long as your textures can be stretched easily (hello simple gradients and flat translucency) you can scale the underlying shapes freely and maintain sharpness and pixel perfect visual accuracy. In contrast, in iOS 6 world, almost every asset has pixel level graphical treatments: drop shadows and glows that scale horribly and need to be re-drawn and pixel-fitted to support resolutions that aren't simple divisors or multiples of the original.
Secondly, iOS 7 takes a giant step towards layouts that aren't strongly tied to precise pixel positions. The move towards more dynamic physics based layouts encourages designs that are a result of interactions between objects, springs and layers rather than pixel perfect placement.
I completely agree with Rene Ritchie over at iMore when he says:
Where everything in iPhone OS 1 to iOS 6 looked rendered, everything on iOS 7 looks on-the-fly. Animation, interaction, color, type, control, everything.
In addition, Apple has been encouraging developers to use auto layout for some time now. It's not out of the question that at some point in the future a new device might only natively support apps created with auto layout, with older apps constrained to appearing in an iPhone-apps-on-iPad style frame. Auto layout makes layouts more fluid and based on relative placements -- the resultant apps could theoretically scale well and stay looking good.
Thirdly, there are already a number of areas in iOS 7 where views are rendered independently or only loosely coupled to the viewport. The new multitasking interface is a great example of this: