In my opinion there is no way apple will introduce a vPhone in February only to replace it four months later with a completely new model. Makes no sense to do a relatively small production run like that, with the likely effect of ticking off a lot of NEW customers.
So, two options...
The phone introduced in february will be for a one-year run. When they introduce the gsm version in June, the vPhone will get a firmware upgrade to include as many of the new gsm phone features as possible. Then, in 2012, there will be a convergence to a dual band gsm/cdms LTE phone.
Or, apple will surprise us all in February with a dual band phone that will still be a 3G unit with some new features. And it will become available to all the other carriers in June. This would be a nice way for verizon to have a bit of a brief competitive advantage, for which I am certain they would have compensated apple with a wad of cash.
Or option three, which is what WILL happen. They will release the iphone 4 in Feb on Verizon. Then, in June, the iphone 5 will be released for Verizon and AT&T. The iPhone 3GS is discontinued. The iphone 4 price drops to $99. Now they didn't screw anybody,because that phone will be available for another year, just cheaper.
This is EXACTLY what will happen. The iPhone 5 will likely be dual band. Apple doesn't want to create fragmentation by having a newer version avaialbe on one carrier and not another. If they were going to do that, the Verizon iPhone would be updated over the AT&T one. It's not.