iphone_att_chainAccording to some excessively well paid bloggers (read: analysts) at Barclays Capital, Apple will probably choose to extend the iPhone exclusivity agreement with AT&T for this coming fourth generation of the popular handset.

The reasoning behind this is that the data plan for the iPad will be through AT&T, which is taken to mean that Apple is continuing its relationship with AT&T. From a behavioral standpoint, this makes sense: when Steve Jobs is done with you, he really gets done.

Another factor in the analyst speculation (and it is very much speculation as only Apple and AT&T know for sure right now) is AT&T’s recent drive to beef up their networks. AT&T’s long-standing inability to provide the data that iPhone users demand is one of the biggest complaints about the iPhone experience.

What the analysts miss for the most part is the effects that the rollout of 4G will have on the iPhone. If Verizon somehow were able to provide almost nationwide LTE coverage to users, it’s hard to imagine Apple not jumping to get on that bandwagon. When 4G really hits, smartphones will be almost immediately available to work with whichever network has it, and a lot of mobile users fed up with inadequate 3G speeds will move on to whichever phones are on that network. Given the rate at which they come out, that almost certainly will result in Android getting the upper hand.

On the other hand, 4G probably won’t happen this year, so Apple does not have a compelling reason to leave AT&T other than to tap the massive Verizon client base. But moving to Verizon’s existing CDMA infrastructure would look very bad for Apple. A touted feature of the iPhone is that the device allows users to use data while in a call, a feature of AT&T’s GSM network that Verizon does not have. This would make for two different iPhones, leading to differentiation too confusing for most in Apple’s fanbase.