I remember playing Indiana Jones and the Fate of Atlantis. There was a floppy version and a CD-Rom version. The floppy one was around 10 disks, but the CD version had voice dubbing for every line of text.
I didn't have a DVD-rom for a while since I found that I didn't watch movies. But now I have a 5.1 speaker set-up and a $50 sony dvd drive. I found dvd movies look actually really good, especially on a 21inch.
I think it is about time for software, mainly games, to come over on DVDs. The drives are so cheap and usually people can at least fit two drives in a pc, like a cd-r and dvd, and if they have a cd-r and a cd-rom with no more room, toss the cd-rom, you won't be needing it.
Some cheap machines, like an e-machine, just come with a cd-rom, but who ever buys that (probably with an integrated video card) won't be playing something like MGS2. So the machines that are more and better capable of playing recent games will most likley have a DVD drive.
Eventually CDs will be going the way of the floppy. Soon Dell will not include floppy drives as a standard part too.
I can imagine people will have cd-rs for a long time, but mainly for transfering files and DVD drives for software. Just how it was with floppies to transer files and CDs for software until when the cd burners became so cheap.