As Crackle says Roche won the Giro and the TdF without a team - other than the one he bought en route. Now it would be foolish to suggest that a team isn't a handy thing to have - witness the help that Sastre had last year - but if Contador is that good then two mountain stage wins should do it for him.
If Astana splits in to Bruyneel/Armstrong (and whoever Armstrong picks up from elsewhere in the peloton, and not neccessarily from Astana) on the one side and Vino-in-waiting/Contador/Kloeden on the other then that's still two strongish outfits in the mountains.
If Astana splits in to Bruyneel/Armstrong (and whoever Armstrong picks up from elsewhere in the peloton, and not neccessarily from Astana) on the one side and Vino-in-waiting/Contador/Kloeden on the other then that's still two strongish outfits in the mountains.