I think AUS have potentially stumbled on somewhere close to their best T20 XI, looking ahead to T20 WC in SRI next year.
The top 5 of Watson/Warner/Marsh/Dussey/White is perfect. However M Hussey has to be back in the main XI @ # 6, since his experience and ability to play spin will be crucial in SRI conditions.
Smith will be a useful squad player. Him starting will all depend on if the selectors wish to use him and Dussey as the spin bowling all-rounders - or wish to keep O'Keefe as the main spinner in the starting XI.
Lee and Bollinger unless they decline in the next year - should be the new ball pair. Thus this leaves Cummins, Nannes, Johnson, Tait battling for squad places.
Possible AUS XI & 15-man squad for T20 WC:
Watson
Warner
Marsh
Dussey
White
Mussey
Wade
O'Keefe/Smith
Lee
Bollinger
Cummins
Ferguson
Tait/Nannes
Hastings/M Marsh
O'Keefe/Smith
Note: Harris is an outside shot to come in for Tait/Nannes, if the selectors feel he is needed next year, if circumstances permits.