Of course cd's will go the way of dinosaurs at some point.
I am from the time of the "8 track" and have seen them come...ooh and ahh over them...and watch them go as the new format takes over.
I remember people saying they would never give up their 8 tracks. I laughed at them remembering how much fun it was to wiggle the tape in the player so it would play properly...a book of matches came in handy too lol.
I remember how cool a cassette tape was and had a nifty splicer so I could make compilation tapes and cut out the extra tape.
I would presume that the next format will be pure internet download, etc. It seems to be the direction that many use now and may prove to be best. I'm not sure how it will work out for home audio though. Hopefully the quality of the song, etc. will be as high as possible. For the car I have everything on my ipod nano 16g. It holds all my music in varied playlists to suit my taste. I also love podcasts and it holds all my podcasts as well. I and many others literally can carry most, if not all, of their music catalog in their pocket with instant access at all times. I no longer steer the car with my knees while sifting through my cd case looking for something that interests me while my wife clutches the seat and complains that I am going to kill us all LOL. Now it is just a click.
Generally there is no downside to new formats if done correctly.