Graphics have a finite limit. Look at Skyrim, how much more detail into faces can they manage? How much more detail can you put on each tree? Look at how little graphics in games change in the last little while and how wildly they developed from early PS2 games to late PS2 games. I severely doubt that we will ever again have nearly as large a gap to span as there was between Oblivion and Morrowind. For people who didn't game at that time Morrowind's graphics make it nearly unplayable, I doubt that such issues would be half as drastic Oblivion to Skyrim, or even TES6 to Oblivion.
Nearly unplayable? Morrowind's graphics aren't that bad! Especially modded, look at this, it's beautiful.
http://reinspired.files.wordpress.com/2011/05/morrowind-with-mge.jpg
http://www.tesnexus.com/downloads/images/5535-1-1193035109.jpg