Certainly there is a consistent flow of young musicians emerging, an admirable fact which in this country anyway I see as almost entirely attributable to the inclusion of jazz in music college curriculums in recent decades. This means that a significant part of the "small and hermetic fan base" for jazz now consists of young musicians.
I am sure that jazz will survive in the long term, but only through and in the academies, as has happened with some European classical musics which no longer have a popular following but which have been preserved..