I am not an insider to Apple or VZW... I can only offer some logic to you which I hope you all can follow.
1) Apple's job is to sell products. By limiting their iphone to one carrier for a few years allows a few things. first a public beta to resolve issues, develop more marketable products (app store) and collect a ton of data. Now I think iphone has transitioned into the device to desire. the demand is there... Why would they want to continue to limit their market share to one carrier in the worlds 2nd largest cellphone market?!?!? I can't see any business logic to why they wouldn't.
2) VZW's job is to obtain new customers. VZ has the US market on lock down. They're holding it down like a fat man on a see-saw. They have the largest customer base and best network available in the US. To push them to the AT&T of wireless they need to obtain the iphone. The amount of sales & premium costs they can charge customers just makes business sense.
With those two arguments being briefly laid out... I see the iphone coming out after June 2010 to "all" carriers. the AT&T & Apple contract expires around that time so I would imagine we'll be something coming out then.