Several years ago, in a talk given by Marin Alsop, she stated that she was not overly concerned about the aging demographics of orchestra audiences.
Her premise was one that I had not considered, previously. Her idea was that for many, "classical music" is a taste that one tends to develop, later in life. The subtle spiritual nuances, and emotional values represented by that kind of music is often lost on kids in their 20's (for instance), who crave excitement & loud music. Alsop's idea is that as we age & slow down, we start to develop more introspection, and an appreciation of the more subtle things in life. [All of this is paraphrasing, by the way!]. Hence the people you see around you in the auditorium tend to be middle aged & up!
On a parallel note, a friend told me of an article that he read, in which they talked about a renovation which was being made to the Chicago Symphony Hall, some years ago. An old 1960's newspaper was discovered in a wall which was ripped down. In that paper, was an article which heralded the end of classical music, because most of the people in the audiences for symphony concerts had grey hair, and presumably would be gone in the near future, leaving the auditoriums empty! Well, I presume that most of those people are gone by now (unless Willard Scott has been featuring them on Smucker's jars, lately!).
Perhaps Ms. Alsop is on to something, 'cause we seem to have a new crop of "grey heads" populating auditoriums now.
Restaurants, like orchestras operate very close to the red, if not in it. 
It doesn't have to be classical music either, it can be anything. The point is that people just need to stop and listen, and learn how to do both of those things!