The Job of HD DVD Players
I assume that the main use of High Definition DVDs will be for movie distribution. Yes, they can also be used for other things but I'm talking about movies because that's who's setting the direction for the competing formats right now, big movie organizations. Just to be clear, I'm talking about DVD players that will play HD-DVDs or Blu-Ray DVDs.
Why we don't need High Definition DVD Players
Your broadband internet connection is capable of streaming HD video (it is or will be soon enough). You want to watch a movie so you pay a small fee and you can stream the video and watch it on your TV. No fuss, no muss.
Scenario 2: Your TV service provider (i.e. cable, satellite, Telco) offers on demand pay-per-view in high definition (they can do this already with standard definition TV). You get the movie for 24 hours and can watch it as much as you want.
One final thing: Some people may argue that because not everybody has broadband access or cable or satellite that these scenarios are not feasible. That may be true but I think the case still holds true. If you're talking about people who can't afford these services, or don't care to purchase these services then are these same people going to go out and purchase an expensive High Definition DVD player? I doubt it, as they too will not need a High Def DVD player, because they don't care to own one.