They have been disrupted in markets where phones compete on price. Their most successful market, by a wide margin, is the one where phones are capped at $200. The comparison to BMW that is often made is laughable. If only BMW sold to dealerships who then turned around and sold the car for the same price as a Toyota. It's a droll-worthy position to be in, that's for sure.
It would be interesting to see how the U.S. market changed if there were no subsidies. My guess is that payment plans would be more common so it wouldn't be such a tremendous blow. But I always wonder if "good enough" Nexus style devices would become more popular and the Galaxy Ses and iPhones a little bit less.