There's a lot of rumours floating around on the iPhone 6. 4.7inch, 5.5 inch screen.. I'm gonna focus on the screen. Do you remember the transition from iPhone 3GS to iPhone 4? The screen went 'retina'. The way Apple handled this, was to double the resolution (double both horizontal/vertical pixel count) of the 3GS screen, allowing apps to be easily backwards compatible on the iPhone4. All developers had to do was increase the quality of their app assets, and the app was retina-ready. When iPhone 5 was released, extra space was added to the bottom of the screen. Easy backwards compat too. When Retina iPad came out, the same thing - doubling of resolution. When the mini came out, it was same resolution as non-retina iPad - easy compatibility. When Retina iPad Mini was release, the same thing happened - doubling of the resolution, easy compatibility. So, assuming a 4.7inch iPhone 6 exists, what will happen? I say doubling of resolution: iPhone5: 640 x 1136 @ 4 inches = ~326ppi iPhone6: 1280 x 2272 @ 4.7 inches = ~554ppi. LG G3 has 534ppi. I am sure Apple can pump out such a screen above. The result? Easy backwards compatibility.