Does AT&T turn into a pumpkin in June?

Broadpoint AmTech's Brian Marshall predicts that the contract that gives AT&T exclusive access in the U.S. to Apple's iPhone expires in June 2010. He also says that Apple is now getting a $450 subsidy from AT&T for each iPhone it sells; after June, that subsidy will be reduced to $300 for all carriers, domestic and international. He also says the 4% of AT&T subscribers who use the iPhone consume roughly 40% of the network's bandwidth.