If BB is'nt pulling in the ratings then the show has to die, it's the way of the world, only banks can escape the forces of supply and demand. It's had 10 years and i think the format has been twisted, reshaped, twisted, reshaped again, and is possibly reaching it's natural end.
Only a handful of shows on TV have managed to stay alive until they are old and grey, Coronation st, Eastendos, Countryfile, to name but a few.
I think it's dead.