This is not a spoiler, just my opinion. But at this point I don't see a scenario where Sandra doesn't win. If she makes it to the final 3 I think she is a shoe in. The only possibility is if Parvati thinks she has a better chance against Jerri and Russell than Sandra and Russell and takes Jerri instead.
But my guess is that Parvati will think she has a better shot with Sandra because she is also a previous winners, so that would negate that aspect. I think Sandra has this.
I have really grown to respect Sandra this season, great player, and if she wins, she'll go down in history as the only Survivor to ever win twice!! She is by far the best player ever, that sucked at challenges. She is great at every other aspect of the game, and knows how to strike the perfect balance of flying under the radar while making bold moves.