I doubt the HD game thing would be exclusive to HD player boxes. I could see them shipping games in both formats.
But there is a rumour that the HD XBox rumour is false...
http://www.next-gen.biz/index.php?option=com_content&task=view&id=8509&Itemid=2
Who knows? And in the end who cares? The games will keep coming for 360 on DVD, I am sure of that...