fr0g:CD will be dead, very soon. In fact I would stake my house on 2 things... It will be as good as dead within the next 10-15 years, and 2...Vinyl will outlive it... (And imo not for sonic reasons, but for tactile, and obsessive reasons)
'MAMW£50&NB' will keep CD alive for a while yet (Middle aged man with £50 and no broadband) and it will be kept alive almost excusively on Amazon (high street CD sales will be dead in 5 years at the very latest).
However, once the middle aged men ARE people who grew up with the internet (very soon now) and once ADSL (or Cable) has reached everywhere (got to happen one day), then 'beermat' formats like CD and DVD and Blu-ray will fizzle out. (DVD last of all I think). HDDs in computers will soon all be the 'no moving parts' variety and will become even cheaper and far higher capacity than the present-day head-crash prone HDDs. Hopefully the big operators like iTunes will soon have affordable lossless format downloads.
Yes, Vinyl will rattle along as a quirky niche product with it's own unique appeal and more budget/mid-price turntables will sprout built in phono stages and USB outputs. (Even Rega if they get their head out their a##e and build a USB equipped Fono-Mini into their P1) It will not disappear totally for a couple of generations - if at all - but obviously will never be huge again.
The problem with downloads is that they MUST become cheap, good and easy and universal. LP, CD and even the humble cassette were all universal. That must be the key factor. Not just easy for geeks, or easy for hi-fi buffs, or easy for one particular age-group, BUT easy for everyone (from 5 years to 95 years) to download universally available, universally playable, high quality, lossless music that can be played anywhere on anything (car, home, hifi, PC, Mac etc.)
Whilst we still have a confusing plethora of download formats occupying a wide spectrum of cost and quality and compatibility then a lot of people will still want CDs, despite their occupying a late 1970's technological dead-end.