Concerning future formats though, it seems to me that a major problem with optical media is the transfer rate limits. To achieve truly advanced image quality beyond the current 1080p TVs you'll need something with faster reading than even Blu-ray or HD-DVD I'd imagine. So whenever that finally comes along we should see DVD pass into obscurity.
To achieve 1080p at 60 fps (which would represent 24 fps, analog film best I'd imagine) using Blue-ray or HD-DVD and the VC-1 codec, you need at least a 4x drive (1x is at 36Mbps for both models). I don't believe there are any Blu-ray or HD-DVD drives that fast available on the market yet (hopefully the PS3 will be at least 4x but it will probably be a 2x drive). Even then, higher resolutions might be nice someday and that will probably require a new format altogether. Though, a lot of home users might never want higher resolutions and thus HDTV might be it for a very long time to come. I really don’t know.