I agree that exposure would have a positive effect on participation in enjoying high-end audio, but I think the estimate that at least 1/2 would convert upon hearing a very well set-up system is much too high, especially if your definition of "audiophile" is at all demanding. Certainly far fewer than 1/2 of the people that audition my system convert (or even sit through very many songs) - in fact the only person I've ever had get real interested was somebody who's already on the path. Maybe my system doesn't meet the criteria of exposure being discussed here, but I'd bet that it does, but in any case it's a pretty common theme that non-audiophiles who hear a nice system, even when they acknowledge awesome sound, don't show much interest in actually owning one.
That said, I've always agreed that exposure would do a lot to promote the higher-end industry. Put decent systems into CD stores with a sign saying "Displayed by .....". Repetitive exposure would quite possibly work a lot better than an individual session.