Also, I think there is only a marginal improvement from the DVD to the HD-DVD format. It's not like it was for VHS to DVD. The DVD format introduced some fundamentally crucial features over VHS:
VHS to DVD
- it was digital so there was no loss in signal quality over time
- navigational improvements; you can skip, use the menu to browse (no need to rewind!)
- the DVD is more compact than a VHS tape
- significant increase in video quality
- support for mult-language, subtitles, widescreen, etc.
- extra features like deleted scenes, commentary, alternate endings, etc.
- can be mailed in a small envelope (see Netflix)
- can be backed up digitally
DVD to HD-DVD (or Blue Ray or whatever)
- increase from 480p to 1080i HDTV format (tough too tell the difference)
- more expensive
I think that all the significant improvements were covered in the VHS to DVD format upgrade and the benefits of HD-DVD are not significant enough to matter to the consumer.
I would put my money on high-quality streaming video services for the format of the future.