Rarely do we get a shot of the Immunity Challenge leaving 3 members left, so we speculate this shot of Ian and Tom going down a zip line is the Final 4 challenge. Who wins out of the 2? It appears that Ian has some issues that involve his height (contact with the water will slow him down), giving Tom the edge.

However, further evidence shows that Tom will go on to win this game as we see the Final 4 sitting at Tribal Council, and you can see Tom bearing the Immunity necklace. Click the image to enlarge it. He will be there for the Final 3, and if it is endurance, which we expect it to be, he will likely win that as the stubborn, Irish man.