I expect consumers with HDTVs will make a gradual transition to the high-definition discs over the next decade, especially after the old analog broadcast frequencies are shut down in 2008 or 2009.
Unfortunately, the current plan is to prevent movies from being shown in high definition on most current HDTV sets, and forbid the creation of convertor boxes that would allow high-definition viewing on them.
So owners of most current high-definition sets will have ZERO reason to want to switch.