John Valentine reports finding a colony with no brood and about 10 of what he
describes as supersedure queen cells, some of which had emerged.  I think it
more likely that they were either swarm or emergency cells.  I don't know what
the beekeeping season is like in his part of the world.  Are drones still
being reared.  If so he has probably just lost a swarm.  If not they are
probably emergency cells caused by the loss of the queen.
Supersedure cells are usually few in number, say 4 or less,  and are of a
similar age.  They tend to be near the centre of the brood frame rather than
around the periphery as swarm cells tend to be.  This is not an infallible
guide and the only true test for supersedure is supersedure.
As John refers to the lateness of the season my guess is that they are
emergency cells.
Chris Slade