Both of them don't have to.
But somebody else then has to, Watford or Wet Sham. And even that only works if we don't get anything from our last three matches.
Nothing's impossible, I agree - but what is more likely? Us losing five in a row, or Villa and B'Muff winning two out of the next three (and both Watford and Wet Sham picking up more points than us too)? Freak result after freak (or at least unlikely) results could send us down, but it would take a lot of freak results for that to happen.