After browsing this thread, it is my new goal to teach all my auto-only friends how to drive stick. If there is enough of us out there, and our numbers multiply, they will continue to build them!
Notice also that this low number of manual car purchases are also relative to the fact that a large majority of people buy boring cars like Corollas, Camry's, Civics and Accords. If you start to look at fun cars, like Subaru's new WRS STI that is currently sold manual-only, a much higher percentage would have the 3-pedal option checked. Sure the mainstream will move towards auto-only, but there will always be a place for people who have the mental and physical fortitude to shift their own gears and prefer to tell their car how to drive, not the other way around.
PS - North America isn't the only place in the world where cars are sold, and North America is about the only place you'd find 6% of the population driving manuals.