There are also non-performance punk photos, such as Dennis Morris's portraits of Johnny Rotten, that have such an aura of threat and promise — again, the aura of anything can happen, that both good and evil (i.e., the performer) are looking us in the face — that they convey the same sense of life. You take Johnny Rotten's thousand-mile stare — compare that to the curl of Billy Idol's lip. One opens up the landscape, one closes it.
The past decade or so has often seemed ripe for a social uprising that never materialized. Americans have rarely been more fed up with their government, or more ashamed of it (perhaps this is about to change). Many musicians speak out politically, but few influence the zeitgeist through their lyrics or public actions — outside of tabloid fodder. Concurrently, photography has lost a lot of its import with the rise (and, I suppose, fall) of the music video, and then the internet. The static image will remain a fixture of music journalism and art, so long as we have newspapers and magazines, but do you think it'll ever "make a difference" or "capture the mood of ___" again? (I've been thinking of it this way: in thirty years, would anyone be interested in a photography show of contemporary musicians?)
I could be short-sighted, but it doesn't seem to me that photography played a significant role in the iconography of social and political upheaval in the 1960s, especially regarding music. That was carried aurally. It isn't the film of Martin Luther King delivering his address to the March on Washington but the sound of it that has become part of history. It isn't performance footage of Bob Dylan singing "Like a Rolling Stone," let alone a photographic image, but the song on the radio for 45 years that, at first announced the tearing up of all boundaries and, since, pointed toward a similar event (or back to it).

The question of whether the sort of images that are in the show now will be of any interest in the future depends on how such a show might be put together. Let's say no cultural memory remains of who these people are — that would require one approach. Let's say there's been a bizarre revival of interest in the periods in which these people emerged, so that everyone does know who they are, and, in some distanced, convoluted way, cares — that would open up other doors.
Ultimately, photographs, which are presumed to record reality, work through silence and mystery, and the silence is part of the mystery, and the mystery is part of the silence. To the degree that a photograph reveals reality directly, it will have little lasting value, or interest beyond the journalistic. But Julia Margaret Cameron photographs are still mesmerizing: less as a record of Victorian attitudes and fantasies than as a vision of a sort of angelic humanism, an epic of pre-Raphaelite splendor. With the pictures that made her famous, Annie Liebovitz's work calls attention to itself before it does anything else; the figures she is putatively photographing work for her. Whether this will make her pictures more interesting in the future or less so, I have no idea. Think of Whoopi Goldberg in the bathtub filled with milk. In 50 years we may not know who Whoopi Goldberg was, or care, but the resonance of blackface will remain, and the picture may be one of the most entrancing and rapturous versions of that version of America we have.