Slightly subversive thoughts - what if there are new genres developing, somewhere, but we're simply not hearing them, because there's no marketing engine behind them?
New Musical forms may be created by artists, but new genres are as often as not created by reviewers, critics or marketers, trying to define, even pigeonhole, what they think they're hearing. See back to KuruPrionz' remarks about all the varied bands, and sounds, that got lumped into New Wave, or Art-Rock/Symphonic Rock/Prog Rock. AFAIK, many of the bands named were trying to break out of established Pop and Rock forms, but record labels, and record stores, needed a name for what they were selling.
Even if someone does try to sell us a "new" genre, are we really buying it? I remember a literary critique from somewhere, to the effect ". . . there is much here that is good, and original; however, those parts which are good are not original, and those parts which are original are not good." Applies to Music, too.