I'm maybe not sure what you're asking, but why would it NOT be viable? Every computer comes with some sort of drive, a DVD player or writer, that will still read CD's. and most people still have CD players.
If you expect to sell a very small quantity, you can burn CD-R's yourself on your computer if it has a CD/RW drive (whether it's an audio CD or CD-ROM with computer files doesn't matter). There are companies that will burn any quantity of CD-R's you want for about a dollar or less each. If you need several hundred copies, you can have CD's mass-produced (these are The Real Thing, like commercial music and software come on, and they're more durable than CD-R's) for about a dollar each (less at higher quantities).
There are surely businesses that do "CD-ROM on demand"... I think soundclick.com and other music host sites do that sort of thing for music CD's (a customer orders a CD and Soundclick burns a CD-R and mails it).
So let me clear this up: Do you want to make your book available as an "audio book" on CD? This would be called an "audio CD" rather than a CD-ROM, and would play in any CD player*. It seems I heard that the Audio Book on CD format is as popular as ever.
And I can tell by POD you mean print-on-demand, but in this context I keep thinking of Podcasting... (never mind)
* CD-R's might not play in some older CD players, for various technical reasons. If you make mass-produced CD's (a several hundred dollars investment), they WILL play in ALL CD players.
If you really want to do some reading, there's more info than you probably want at
http://cdrfaq.org
