Industrialized nations certainly have greater penetration, but the fact remains that the world is still on the communications runway, and not even yet at full throttle. I don't think in my lifetime we will see HDTV more than just beginning to become a mass medium. That means to me that anyone who proclaims that HDTV is a bottom up item is wrong. They are still reaching downward from their aristocratic birthplaces for ever-greater users. HDTV will do the same.
Cost determines the rate of assimilation.
Nothing is free. The rate of diffusion is pre-calculable. Since entering this business I have advised my clients that to construct a rational plan and policy that provides local bottom-up HD services for every person 'suddenly' is misdirected. And, no rational plans have surfaced to prove that council wrong. You can understand the need for general preparation for it, but any artificial forcing of the marketplace is doomed.