>> Maybe the new codec for MPEG-5 will be cleverly named DivXviD...
If you are seriously interested in compression, check out the book "An Introduction to Data Compression" by some indian guy whose name starts with K (sorry, too lazy to look it up right now). There are a couple of copies on ILL, one of which will be in my possession in two weeks

Anyways, to make a long story short, as it stands now, IF there will be a mpeg-5 standard, it will mainly be focusing on the wrapper, not the actuial compression. We are starting to hit some serious walls in advancing lossy video/audio compression, which there is still a ton of work to be done with the wrapper. Ask anyone whose had to produce a DVD or mess around with subtitles and multiple audio tracks in MP4's and you will get quite an earful . . .
-Chu