I don't believe iPhone isn't going anywhere with any other carrier, other than AT&T. Just because Apple iPhone is such a big global cell phone that are all baisically on GSM networks.(in other words, iPhone likes to go international & travelers can have a better experience.) Also, CDMA is becoming old, while Gsm is more modern and Apple likes to roll with modern.
As for the next generation iPhone,
Who knows if it'll be 4G. it's too early for it to be 4G, especially if AT&T and/or Verizon is gonna be working on it in the future. The only way they'll roll out a 4G iPhone will be if Apple attaches itself to Sprint, who is currently the only 4G network in America.
Camera: Expecting a 5 megapixel, but Apple wouldn't do 12 megapixel, for SURE! atleast not now.
I can see Apple improving the camera and video features also.
What I would like to see is "pinch & zoom" before snapping a photo and video.
It'll make more sense because of Apple's multi-touch quality and technology and can be a real big help to those who like to get those up-front like photos.
That would be a big plus, and possible for Apple to introduce in their camera app on their next generation iPhone, and update. if not, there is always next year
Design: Most most most likely a new disign, most likely slimer, etc.
Don't be expecting a physical or Slid out physical keyboard. There is a reason why Apple talked about it in WWDC '07 and there's a reason for adding a smart virtual keyboard.
Battery: I'm real positive that Apple will boost up the battery life to atleast 7 hours of talk-time. My highest hours of guess,(or atleast 9 hours, to the MAX.)
Resolution: Positive that Apple will also boost up their resolution, but not too many. And i'll be super suprised& shocked if Apple releases an OLED screen. Very very "suprised"(doubt it they'll get an OLED screen.)
User interface: Can be worked on, and am probably expecting a 4.0 update anytime soon. It's highly possible.
As for the UI, i'm real comfortable as how it is for myself.
Gigabytes: I could definitely see Apple's iPhone jump up to 64 gigs. Throughout the 3 generations, we've all seen and noticed a trend of gigs just
doubling on iPhones(and iTouch.)
Flash?: Apple fans and iPhone owners seem to be concerned and are always wondering, "damnit, when are we getting flash?" As for flash, i believe there 60% chance of Apple introducing flash in the 4th generation iPhone.
I still have no clue where & why the flash hasn't been included yet. Let alone, it'll look ugly on an iPhone. But there are few potential places to add the flash at.
Like, if I were to build an iPhone myself, and if I were in Apples shoes, I would add the flash on the Apple logo,meaning,.. Very, very bright flash. Especially if it were an LED flash. It'll look perfect on the Apple logo, just because it won't have to ruin the original & amazing iPhone look on the back. and it can have a bright MacBook apple logo brightness to it also, whenever the phone is in use.
Very clever ;D
Front facing camera: In no way, would Apple introduce a front facing iChat camera on the 4th generation iPhone. I mean, that'll be a very nice plus, I'm not gonna lie. But would any telecommunications service be healthy enough to support that yet, especially with over a million iPhones out there in the world? But than again, maybe wi-fi hotspots? Hmm, who knows. Still, I don't believe Apple would allow front- facing camera in 6-7 moths. It's just too much at the moment.
Don't get me wrong, I'll like this iChat camera, but maybe more suitable in the year 2011 and beyond, just not now.
Overall, these changes are just expectations that I ''think" Apple will unviel with the 4th generation iPhone. Hopefully better ideas may come out soon.
Just don't expect Verizon Wireless. (I'd also be suprised.)