I don't think the market for quality audio equipment will disappear, but I think it will contract. I'm in my late 60s and as a kid the family listened to our stereo (such as it was) for family entertainment. That entailed actually buying physical media and loading it up on the turntable. Recorded music has been commoditized for young people with ITunes and a cell phone-no more "ritual" involved. There are exponentially more entertainment choices and music is more likely to be a background thing while they are working out, etc.Quality sound is not very important in that context. One of my great pleasures is spending a couple of hours, or more, just listening to music and nothing else-my kids (in their 30s) don't get that at all.
I also think the disappearance of brick and mortar stores contributes to the shrinking market. How many young people have actually heard a reasonably competent system? In the old days, audio stores were plentiful and even if you couldn't afford to buy you were exposed to the experience if you were curious enough to walk in to a store. That's not happening much these days.