I suspect that folks who really care that it's an iPhone and not an Android (or potentially WP7, if that ever gets off the ground) have already made their move.
Remember, though, that the smartphone market is far from saturated. You could argue that it's barely been tapped - dumbphones still compose the vast majority of the U.S. phone share. Upgrading from a 3 year old dumbphone is a prime opportunity for a consumer to rethink their phone carrier. I imagine Sprint lost a lot of first time smartphone buyers to the iPhone thanks to Apple's "easy-to-use" reputation and the massive hype of every iPhone debut.
Remember, though, that the smartphone market is far from saturated. You could argue that it's barely been tapped - dumbphones still compose the vast majority of the U.S. phone share. Upgrading from a 3 year old dumbphone is a prime opportunity for a consumer to rethink their phone carrier. I imagine Sprint lost a lot of first time smartphone buyers to the iPhone thanks to Apple's "easy-to-use" reputation and the massive hype of every iPhone debut.