20-Year Prospect
Recording, synthesis, mixing, and delivery of audio are not going anywhere any time soon. With expanding media industries and advancing technologies in sound, now is a better time than ever to get into this field...according to the numbers, at least.
Audio engineering at the professional level will likely always be a job, but as technology advances, a lot more of the engineering may be handled by computers. People are already recording albums on their own because computers have made music production so much more automated. The job may change a little as lower-end work gets taken by computers, which will make it harder to score experience that leads to more professional work.
You may have to market yourself a little better at first as the years go on, but this career is generally on the upswing.