If the final selection has been made and suddenly one or more of those housemates was revealed and a picture or pictures appeared in the Newspaper or something.
Maybe, that housemate or housemates would not get the chance to go in any longer?
That is always a possibilty...
Don't forget, there will have to be reserves, just in case. I would say that Big Brother will have three girls & three guys as reserves.
nodisharmony
