Wade did make that good hundred in the second test and has been beating down the door with a lot of domestic runs. I do think that the Head experiment is on a knife edge, he's averaging low 40s after 12 tests.That's true but Wade and Head aren't cutting it as test batsmen. I suppose as you say we have enough bowling depth to do without. Maybe in India they would be happy to have extra bowlers with the extreme conditions.
To be a true test all rounder you probably need to average mid 30s with bat and ball and I don't see any Australian players with the ability to do that atm.