I admit that I only read through the first 10 of the current 14 pages of posts, but I haven't read another comment from someone who shares my opinion: I don't care whether the iPhone has a 4" display or a 5" display. There are things I'd change about iOS and other Apple products, but the reason I upgraded from the iPhone 4 to the iPhone 5 last December without considering competing phones is that I've been in the Apple ecosystem for years, I love Apple products overall, and I have a Mac, an iPad, and a large collection of iOS apps. I'm not one of the "Apple sheeple" who "drink the Kool-Aid" and think that everything Apple does is great. I don't hate non-Apple products. In fact, I've been using Windows PCs since Windows came out, and I'm perfectly fine with the Lenovo laptop running Windows 7 that I use at work.
For my personal use, though, I have neither the time, the inclination, nor the money to switch brands and platforms every time a manufacturer comes up with something that's slightly better in a couple of aspects than what the competition offers. I have no problem with people who switch phones once or twice a year to keep up with the latest and greatest, but that's not me. There are tasks that, for me, are best done on an iPhone, tasks that are best done on an iPad, and tasks that are best done on a Mac. I might be wrong, but I don't think that increasing the iPhone's screen from 4" to 5" will make it significantly easier for me to do what I do on the iPhone: take pictures, listen to music, check my calendar, use the calculator and other conversion apps, find directions to places, play Scrabble to kill time, and so on. I look up information on the Internet on my iPhone when I need to and I'm not at home, but for casual browsing, I much prefer the 9.7" screen of my iPad 4. The same goes for reading ebooks and watching YouTube videos. For movies, I prefer my big-screen home theater. For typing-intensive tasks, I prefer my Mac. For processing photos, I go back and forth between my Mac and my iPad.
On the other hand, if the iPhone does go to a 5" screen, I won't mind. I might even like it better than the current 4" screen. But for me to jump ship from the Apple ecosystem, the competition will have to offer an overall better user experience in the areas that are important to me, and probably at a lower price. I suspect that the same holds true for the majority of iPhone (and probably Andoid phone) users. Are there any data on what percentage of smart-phone sales are by people who upgrade frequently to have the latest and greatest, as opposed to first-time buyers in new markets, or people who upgrade because their current model is getting too slow or otherwise lacks compelling new features? In other words, is Apple really in danger of losing significant market share if they don't switch to a 5" iPhone screen?