In order to even upgrade to the iPhone 5, existing will have to take a new data plan. No more "free-bees". Consumers would have to make the choice to either keep their current data plan which is fairly affordable or switch to the LTE network which all iPhone 5's run on. That will without a doubt influence the new customer's decision. Many people can not afford their phone bills now, the iPhone 5 will run them dry.
To sum it up though, some people do have the capital to purchase the new iPhone and some already have. Apple has already gained that loyalty. To maintain it though, they might have to give us consumers more bang for the buck.