Verizon will say whatever it can to leave the impression people could switch to them as a means to maintain mindshare. However in reality AT&T has an exclusive, that exclusive is valid through mid-2010 and possibly longer on the original device.
If there is a new form factor device, all bets are off, and if Apple wishes to make a "crippleware" phone for Verizon's dead-end version of 3G, that could happen too, but it will not be "the" iPhone.
The only area where Verizon has a slight edge over AT&T (note pun) is LTE. Verizon has more nodes deployed and tested than AT&T as of today, at least as far as public disclosures have indicated.
If the new device has LTE as one of the radio options, which I hope and believe to be the case, then it would be compatible with either AT&T or Verizon in the late 2010 to 2012 and beyond release timeframes.
The only problem there is LTE is not well deployed by either and they both publicly state 2012 for general LTE rollout on a widespread basis. The fallback on a new form factor device is 3G and 2.5G and wifi, so we have the Verizon style 3G dead end issue again. If the new device also has that protocol via the Qualcomm chip, then this rumor might make sense. But again only for the new device and only 2H2010 and beyond, and only if it is ALSO accessable on the AT&T network.
Desperate rumor or factual leak? Wanna bet?
Rocketman