It will largely depend on whether or not they decide to revive the old rule about not being able to choose the person you've been rooming with. Charla will either choose Dave or Keith, depending. And since the Inner Circle doesn't like either of them, they won't pick Dave or Keith (unless they feel particularly nasty and want to torture the poor soul for a week until they kick them off). Whichever one doesn't get picked by Charla would then need Tara to pick them to complete the alliance. But I don't think Tara can be trusted to make that choice, so the leftover guy might get picked up by Toni (if Holly chooses Scott) or Amy (if Holly chooses Beau). Alex of course will pair up with Kristin.
So I think anyone but Charla (and possibly Kristin) is at risk to be sent home. Charla's safe with either Dave or Keith. Kristin will be safe with Alex unless they bring back that old no-repeat rule.