Rumors from the Apple supply chain indicate that the Apple iPhone 5S will have a larger 4.3-inch display. Even if Apple maintains its current 640 x 1132 pixel resolution, the display would still have 302 pixels per inch, and hence qualify as a retina display. The change in the screen size is also supposed to delay the release of the iPhone 5S until the end of the year.
I do not know if the rumors are true, but a 4.3-inch iPhone would really be nice. I always felt the 3.5-inch display was too small. The 4-inch display was much better. A 4.3-inch display will improve the typing experience for those of us who like typing in portrait mode. Personally around 4.2 to 4.3 inches is my favorite screen size, or 4.5-inches if part of the screen is occupied by Android Nexus type soft buttons.
It looks like we will be waiting a long time to find out if this rumor is true.