A 4" iPhone doesn't make sense to me

The linked post above made me think about the rumour, that the next iPhone will feature a 4” screen. I don’t think it’s going to happen and these are my reasons:

• The increase in raw screen size in minimal, while the device has to become significantly bigger.
• Assuming Apple won’t increase the resolution, they would loose the ability to convincingly call this a “Retina Display”.
• A new display-size demands new expensive production lines.

I’m not dismissing the possibility, as Apple tends to spend a lot on R&D, but they also rely on economies of scale to keep their profit margins up. Changing the size of the display — which was probably extensively researched and tested and has worked very well for both Apple and its customers — would require large investments.

For me the 3.5” screen size hits a sweet spot: It’s big enough for me to type comfortably, even though I have big hands and the device is small enough to fit comfortably into my jeans pocket — and don’t want to carry a murse just for my phone.