Everyone keeps discussing CDMA, tethering, 3G, speed, multiple data streams, etc. What they haven't touched on is the ability to do what the original purpose of these things are: make a call! I have my 4 year old Verizon cell phone and an iPod Touch for precisely the reason that I NEED my phone to be good at one thing consistently: making calls.
Watching streaming video and all that jazz is all fine and dandy, but if I can't consistently make phone calls, what is the point? Why should I trade in my phone that I have now? Every friend I have that has an iPhone is hooked on it's features, apps, etc, but if I ask them about their calls they say "yeah, it sucks, I drop calls all the time." Or when I call my own mother, and her iPhone drops in and out, but then call my father's phone on Verizon while he is standing less than 2 feet from her and there is no problem at all.
Would I like to combine my iPod Touch and phone into one? Yes. Am I willing to give up being able to make decent, reliable phone calls? No. It's that simple. If Apple can bring the iPhone to Verizon, I don't care what kind of network it is on, so long as I can speak to people with reliability.