The thing about blu-ray especially (50 GB discs) is that it would be easy to put many h.264 variants on disc. Watch the near lossless version on your 50 inch 1080p via a Blu-Ray player for the theater experience. Then, download a 720P compressed version to any blu-ray equipped mac for storage and streaming to AppleTV anytime. Lastly, download yet another version to itunes for ipods.
The last piece of the puzzle, AVCHD (also part of the blu-ray spec), could be an enhancement to a mac video card to facilitate transcoding of AVCHD files on the fly both for streaming and to speed editing of those files in imovie/FCE/FCP. That way, personal video would be easy to ingest, store, watch (AppleTV), upload (YouTube, .mac) and burn (blu-ray or AVCHD on DVD).
And yes, as a matter of fact, I am waitng for 45 nm Quad core, a Blu-Ray burner, and HDMI IO on my next MacPro.