HEY DUDES, read this article a couple of months ago, i think it answers the question about whether we will have enough space on a dvd 9, it says new compression technology ALREADY being used for xbox live downloads can compress game data down to 90% (if i read that right) of its original size!!
its called PROCEDURAL TEXTURING.....the future, so its looking increasing likely that we WONT need expensive blue ray.....or will we?
heres the link;
http://www.bit-tech.net/gaming/2006/11/09/Procedural_Textures_Future_Gam/1