Clearly the case is not that cut and dry with audio. Vinyl has been around for a very long time, and will stay around for a very long time as well. I guess one yardstick to keep an eye on would be the percentage of people who enjoy high resolution audio systems that use a vinyl playback system at all.
My prediction is that vinyl will go the way of the dinosaur, but not for quite some time. I wonder how many high-end turntable producers there are today and how many there will be in 50 years? 100 years?