I made a post recently that we shouldn't rest any players for the fourth Test, that I wanted us to field a full strength side and grind India into the dirt. After seeing the full extent of their "performance" in Perth, to be honest, I think we can easily rest a bloke like Siddle or Harris.
The other option is that we rest Ponting or Hussey, or drop Marsh, and play five bowlers. On a flat Adelaide track, we should have no problem setting a total against a mind-crushed Indian attack, whether we use five or six top-order batsmen, and playing five bowlers would allow our bowlers a bit of a break (workload split between five, not four) without running the risk of disrupting their form. It would also allow Starc to make use of the confidence he would have taken from that game. He'll be back out of the side soon, so we might as well get some overs into him while we can and he's confident.