Personally, I would be disappointed if they made the phone bigger. I like the screen size at its current size. It'd be one thing if they introduced a separate model with a larger screen, but don't size the phone out of my reach. As a petite woman with small hands, there's a limit to the screen size of one-handed usability for me.
I imagine the iphone will have a redesign, various upgraded internals, 4G, ios 6, etc.
As for people who think they know what iphone users want, why don't you conduct a real poll? Not a MR poll, but a non-biased, randomized poll of people about screen size on the iphone.
The erroneous presumptions about what iphone users want is starting to grate on my nerves. This isn't the borg collective, so I especially dislike the collective use of "we". We do not necessarily want a 4" iphone or a 7" ipad. Be honest and say you want a 4" iphone or a 7" ipad.