I've been mulling it as well since I read it today, and alas don't have the time at present to get into it. Basically, though, he's right. I was there near enough to that 1990 moment (I started grad school in Media and Cultural Studies in 1991) to have experienced it from the inside. Cultural studies (especially in the US) had indeed started to lose its edge by the late 1990s, though it wouldn't be perceived as such till a few years later. These days, at least in media studies, other paradigms and approaches have come to the fore, not as much "replacing" CS as trying to reinvigorate it (I'm thinking especially of production studies in this regard).

Fan studies has (as always) a problematic relationship with this history. Sloppy versions of it became all the rage during the 1990s, the worst of which more or less verified the critique of CS as "too celebratory" (to be charitable). Fan studies has improved in depth and breadth since then, of course, but I think the old baggage of those days still holds us back.

That said, the bigger meta-question, which Berube's critique alludes to, is what is the point of the humanities scholarship and education? We've been researching and teaching along these lines for over 30 years, and we really haven't changed a damn thing in the world. It's something that most of us working scholars, trapped in the everyday pressures of our jobs, try not to think about. But we're going to have to.