You make a good point on Watto, but does Australia have any options waiting in the wings? I was impressed with Stokes this summer.
Mitch Marsh has potential, but has been in indifferent form in the shield (at least thats what i saw in the couple of matches i went to and crcinfo). Faulkner is probably the front runner, but i dont think he has the bowling ability in tests, and i havent seen him bat enough in tests to come to a decisive conclusion. My favourite to take his spot is Starc, he has a natural ability with the bat, and is severely underrated as a batsman. His bowling is inconsistent at times, but with a 5 man genuine attack, he can be backed up if he fails and when he is on song, he can take 5 wickets in a single spell. However, if Starc or Faulkner were to join, my guess is they'd push Haddin up to 6, but that can imbalance the team and see a drop in Haddins form which is why Marsh is the best choice for the team, even though i'd prefer Starc were to come in.