Right, but the fact that the US effectively doesn't have a low-cost phone market means that it shows what happens when the market saturation of cheaper Android phones is removed, and the market in which Apple plays is (more or less) the entire smartphone market. That's where you'll see the real attrition between Android and iOS either way - except that I think Americans tend to be more pro-Apple than other areas. When people switch between Android or iOS it's usually because they're upgrading (I would assume), which means they've moved from a lower bracket to a higher, or just on preference have changed systems.
At the high end of the phone market the real obvious distinction between Android/iOS was screen sizes. I mean, I know there are other factors and entrenchments and ecosystem buy-in etc, but that's the real elephant. Now that's removed, I would think someone who firstly is already in the high-end phone market, and secondly was on the fence previously or would have preferred an iPhone but saw how dwarfed it was by Android handsets, has a greater likelihood of buying an iPhone 6. And I'm just guessing, but I think those numbers could be quite meaningful to Apple in total sell-through.