There is a middle ground.
Hussey clearly has a few miles left in the tank and Clarke has a long future still ahead of him.
While Ponting may have the former, I really do doubt that his future is long enough for him to reach those extra miles.
So yeah, I'd suggest dropping/replacing Ponting, Smith and Hilfenhaus. Harris is an enforced change and the only other toss up is Katich/Hughes. I'd give the nod to the experienced head, again another person for Clarke to bounce ideas off and also can get through some overs of unappreciated spin, also the fact he's about twice the batsman of Hughes at this point in time too.
Hughes really could benefit with going back and plundering some Shield attacks until Katich calls it a day which won't be too far down the line anyway. Feel quite sorry for the guy about this series, everybody knew he was in pretty horrid form and it's shown.