The physical design of the phone is a big issue because of the fact that the new iOS will run perfectly fine on the 4. Apple can stand up and do a big show about how many new software upgrades the "iPhone 4S" has (if the only thing they have to offer this year IS the 4S), but when it comes down to it, if they keep the same form factor, the only things that are going to be different about the iPhone 4 and the iPhone 4S are the camera and the processor.
If the phone runs perfectly well on the 4, then the processor becomes less important. And as far as pictures go, nobody is using this phone for wedding photography (I HOPE), so the camera aspect won't be a very big deal to most people either. Most people use this camera for crazy friends pictures/video, in the moment...nothing they want to view professionally. Working with cameras for almost 4 years allowed me to see that megapixels don't really matter as much as most believe they do. 1080p video would be cool, but again, not something that MOST iPhone users will need and/or care about.
So, in the end, if they keep the same form factor, A LOT OF IPHONE 4 users are going to stick with their iPhone 4's just because an IPHONE 4S will have nothing worth paying the early upgrade fee for. I used my mom's upgrade to get the 4, so I have my own upgrade this year to get the 5 (if it exists), and if there is nothing but an iPhone 4S coming out, I'll keep my $200. I know my phone is jailbroken, and perfectly set up the way I want it right now so it's going to take some serious incentive for me to drop the jailbreak to get a brand new device.
If the phone runs perfectly well on the 4, then the processor becomes less important. And as far as pictures go, nobody is using this phone for wedding photography (I HOPE), so the camera aspect won't be a very big deal to most people either. Most people use this camera for crazy friends pictures/video, in the moment...nothing they want to view professionally. Working with cameras for almost 4 years allowed me to see that megapixels don't really matter as much as most believe they do. 1080p video would be cool, but again, not something that MOST iPhone users will need and/or care about.
So, in the end, if they keep the same form factor, A LOT OF IPHONE 4 users are going to stick with their iPhone 4's just because an IPHONE 4S will have nothing worth paying the early upgrade fee for. I used my mom's upgrade to get the 4, so I have my own upgrade this year to get the 5 (if it exists), and if there is nothing but an iPhone 4S coming out, I'll keep my $200. I know my phone is jailbroken, and perfectly set up the way I want it right now so it's going to take some serious incentive for me to drop the jailbreak to get a brand new device.