I'd hope that all movies being put on HD-DVD or Blu-ray are transferred in their proper aspect ratio and that the players are then properly programmed to alter that ratio for specific TVs based on what the viewer prefers. That would be the smart way to ALWAYS do it considering how DVDs were often so crazy when it came to aspect ratios.

Otherwise, lordjedi, I don't think new codes would erase the old codes (if they did that would be just-plain sick). So if your old discs need the old code, it will still be able to play them.