All of the currently existing Apps are written for the current screen size 480 by 320 pixels at 163 pixels per inch--and it's unclear what a revolutionary screen-change would mean for older apps. Would they simply run in a letterbox automatically? Would they need to be re-written for the new display? App creators may want to optimize, but that could require significant development work. All-in-all, the change would have big implications for the App Store, which is a primary reason the iPhone remains so successful.

A revolutionary next-gen iPhone packed with a new 720p screen and extra tech implies a similar or even more expensive device, which would have a significant impact on sales. The iPhone is already expensive, its high price is the reason people often cite for not buying one. An evolutionary iPhone, without HD, could go on sale at a lower price, especially if Apple manages to shrink manufacturing costs and strike deals with electronic component suppliers.