Australia have some up and coming cricketers:
Michael Clarke, Michael and David Hussey, Marcus North, Shaun Tait, Cameron White, Shane Watson, Daniel Marsh, Chris Rogers, Allan Wise, Andrew McDonald, Paul Rofe
just to name a few. None of them can break through into the senior team though because it's so powerful, and the only way they can get a game is through injury, and usually they replace players with other players with other ex test players:
Matty Elliot, Martin Love, Andy Bichel, and Stuart MacGill (2nd best leg spinner in the world, and can't get a game in the Aussie side) just to name a few again
So you can see the depth of Australian cricket, and it will still be pretty big in years to come, although the bowling department will have dropped off considerably, without the guns of today (McGrath, Gillespie and Warne)