Photography has actually found its place in serving a universal social function - the reason we don't see anything radically new then is that photographers have stopped searching for the 'meaning' of the medium. We've found it. And it wasn't artists who found it, but ordinary people.
You can look at Harry Callahan as someone who experimented with every facet of photographic seeing, but miss the point that the strength of his work depends on how reflective it is of his ordinary life experience. He photographed his family and his immediate surroundings, just better than everyone else. 'New' in photography can be seen as new subjective concerns or new ways of seeing the same old crap. Isn't the latter responsible for most movements? Isn't it happening all the time, with every new photographer who picks up a camera? New things are being created all the time, they just don't stay new for very long. This isn't a problem with photography, but how small the world has become.
Because photography has found its function amongst the masses, a game changing revolution might only ever happen again in tandem with some kind of global shift in awareness, as the result of a cataclysmic event, because most people are intellectually and creatively average and uninspired. It's people now, rather than artists, who are responsible for photography's real momentum and social influence and I guess it will only ever move in gentle waves. Nobody wants to sail on rough seas!
Nothing radically new in a technological sense will happen with photography so long as Canon, Nikon and friends continue indefinitely playing this slow, cautious game of tech chess.