David Gratton has a terrifying and apocalyptic vision of the near future of CD sales:

CD Sales are about to collapse in the next 12 - 18 months. I don't mean by 5 or 15% (which is bad enough) they are going to utterly collapse. They are going to get destroyed. There will be a 30-50% collapse in music sales in less than 18 months.

I found this extreme picture surprizingly convincing. My own reasoning is that ownership of file-based devices like iPods will reach critical mass very soon, if it hasn't already, and when that happens the majority of listeners will actively dislike CDs.