"WP has been on really high-end hardware -- and sold effectively ziltch. Part of the reason for the mid- and low-end WP is because MSFT is building up market share in areas where there's demand -- developing nations, as well as in parts of Europe, where they told me WP actually has double-digit market share."
I think another one of the reasons at least here in the States is that none of the high end hardware has been multi-carrier. I'm hoping Lumia 950 will be available on all four major carriers here. Also, there's so much fragmentation in the Lumia line it's ridiculous, especially with such relatively small demand in the states. Just release three lines: low end, midrange, and high end. No reason to have 400, 500, 600, 700, 800, 900, and 1000 range Lumias.