Apple don't have a relatively small market share in
smartphones. Asymco likes to quote the mobile phone, not the smartphone numbers to make this stat sound more impressive than it is.
If you do that then it's something like 4% of unit sales share giving 50% of profit. If you exclude people selling millions of throwaway cellphones for pennies and only include HTC, RIM and the smartphone parts of Nokia, Samsung etc. then the profit they make (while still better than the industry average, thanks to RIM and Nokia pulling it down) is much more closely tied to market share and therefore seems much more under threat as Android advances on that front.