The premiere for the film is on tonight and this whole task is all leading towards the film, so I can only assume they couldn't get the film premiere to happen any closer to Halloween.
This task guy on BBBOTS said there will be Halloween stuff going on on the 31st - I very much doubt they'll bother to do a live show though.
I don't see us getting many 'live show twists' this year, hell, I don't see us getting anymore twists at all. Their "BIG TWIST!" for the series was probably Jem going in.