First off, IMO Adam won't win anything. I think he is too nervous and wants to continue "riding the fence" without making enemies. Shelly seems to be better at comps, but I dont think she will win if she somehow stays.
My gut feeling tells me Shelly leaves 3-0. And then Jordan wins hoh.
If Jordan wins hoh, and they want Rachel out, they have to pull a BB5 and lets say Kalia/Adam are up. Porsche wins veto, Rachel goes up and out the door. So Hoh/pov is the only way your safe.