Although it can be done with newer packaged media, I have a feeling that just like DIVX, the customer will avoid it like the plague.
What is currently being done is providing extras via this method where if you have your player connected to the internet, you can access online content like trailers (Freedom HD-DVD), activities (Shrek the Third HD-DVD), and a few others. I'm not really sure if they are actual downloads and not just extras on the disc unlocked by visiting a specific server with the HD-DVD player.
We'd need a big upgrade in the current internet's backbone to support the amount of data needed to be transferred for High Def content delivered this way. At least in a reasonable amount of time or at an acceptable level of quality (i.e. no stuttering or stopping of the video due to connection issues).
Plus, are the movie studios going to keep running the servers needed to deliver the content and are they going to pay for the necessary bandwidth required to stream HD content online?
We've already got access to this technology through our cable companies via video-on-demand. It's been around a while and I don't see Blockbuster's or Netflix's business being affected much by it. And what's better, with VOD you don't have to connect your player to the internet or store content-less discs that only provide access to video from a remote server (I have enough trouble finding places to put all my content-filled CDs and DVDs).

