I think I just figured it out! Forgive me if someone else has already posted this possibility but I believe I know what the next big twist will be, and it is HUGE.

After the next roomate selection and elimination of one of the girls, there will be 8 guests left. I believe that Amanda will inform the guests that the selections they just made will be their final ones and that from here on out the eliminations will come in pairs.

With only I believe 5 episodes left, counting tonight's, and seven guests still to be eliminated, I really think that this idea makes sense.

Just think about how much it will change the game as the roomates will be selecting roomates in order to get rid of whoever it is that they are plotting against (hopefully Amy), and then find out that they will be rooming with their selection the rest of the game. Dave will go nuts if he doesn't end up with Charla, as well as whatever Keith is plotting may be completely destroyed.

Once again, I'm sorry if this possibility has already been explored, but wow wouldn't add a cool twist to the last few episodes of the show.