HDMI 1.1 already supports everything that should be needed by either HD-DVD or Blu-Ray where the 8 bit limitation makes itself felt (both support MPEG-2 and 4). Here is the MPEG-4 stuff that obviates the issues with DVI:

http://en.wikipedia.org/wiki/H.264/MPEG-4_AVC

As far as the competing HD video formats: really, from an audio or video output standpoint there is no real difference between HD-DVD and Blu-Ray, unlike DSD versus MLP.

As far as hi def audio, HDMI 1.1 supports uncompressed 7.1 192/24 audio, this is really all that needs to come out of either HD DVD or Blu-ray to support any HDMI 1.1 compliant receiver/controller and get the best sound quality (sorry DSD fans, of which I am one, big collection of classical SACDs). Frankly the authoring process has more to do with perceivable sound differences between DSD and DVD-Audio than the formats do.

The other formats are simply marketing B.S. on the output side of the players. These players should handle new formats the way a computer's soundcards does, cards only put out PCM, MP3 or DD regardless of the native format for external devices, the new formats are handled in software.

The only possible reason to pass the native audio formats on to a reciever is to put more encoding information in the bit stream to manipulate sound effects, such as breaking out extra channels etc. Frankly, I don't care about this.