Here are my renderings. Far from perfect, I know. Just wanted to do this to create an idea of what a 4" and 4.5" screen would look like on the current iPhone 4/4S form factor. The form factor on the paper is slightly larger than the current iPhone because I traced it. The screen sizes however are exact. Perhaps Apple would be forced to also increase the form factor in order to avoid a widescreen aspect ratio, however you can't deny that both of these, as a retina display, would be pretty amazing.