So, what can it be? A better camera with 8MP camera? No, it cannot be just that. I've long talked about having better battery life. I would have to have the kind of battery life that I have with my iPad but I would have to take a long hard look to make sure that's what I'm getting.
Having A5 chip would not be enough. I think for the most part, the iPhone 4 is plenty fast enough for my mobile use. Don't get me wrong, I can certainly use more speed but that isn't enough either.
A change in form factor definitely will not be enough.
Bigger screens? I wouldn't mind a 4" screen but only if Apple is able to retain the Retina Display quality. I don't know how but I'm sure they'll be able to find a way to make it happen, if it happen.
A combination of a bigger screen and better battery life could do it.