But there is one point to keep in mind. How many different models of Android phones did it take to catch up to one model of iPhone? Just a point.
Sure, but I think the IPhone sold 14M at AT&T last year, but 75-80% were upgrades...call it 4M new users. I don't know any specific Android numbers off the top of my head, but several sold 2M or more. Granted, same thing in reverse with pent-up demand, but as noted there's also more competition.
That there are many more Android choices is also partially why one handset is not going to rival IPhone sales, too easy to switch between handsets and too many alternatives. But at the same time AT&T and VZW are going to have several premiere Android phones that are, for all intents and purposes, virtually perfect substitutes for each other AND the IPhone.
Just saying, if you had to choose between IOS and Android as a carrier, you would choose Android because it's ultimately going to have a much larger share, the number of handsets is really irrelevant. And part of the reason the IPhone is on VZW is because AT&T sales were slowing, reaching saturation - the economics of an exclusive deal didn't work for either party.
And a couple of points bear repeating here. First, if licensing IOS made sense (bottom-line $ sense), they would do it. And about the multiple device argument - Apple is big enough, with the cash and resources, to go make multiple devices and there's a reason they don't. Yes, they would sell more but they would largely be cannibalizing their own sales. Much of why IOS is so good and IPhone so popular has to do with being 1 device, and also really the only device for several years.
If you are talking more devices then you are talking about diluting the brand and diluting the quality, and "marginally" more sales is obviously not a trade-off they're willing to make.