FFA have published the 2011 - 2015 Strategic Plan.
Couple of quotes:
... a vision for Australia to become a Top 10 football nation.
The ambitious target goes way beyond our FIFA Ranking.
Our targets include:
- Qantas Socceroos qualifying for Brazil 2014 FIFA World Cup and reaching the round of 16 as a minimum.
- Winning the 2015 AFC Asian Cup on home soil
- The Socceroos contesting for a Top 10 spot on the FIFA Rankings by 2015 and averaging a Top 20 spot across the period.
Things going against this quest:
- Australia will host the 2015 Asian Cup, thus they'll miss out on scoring important FIFA ranking points in the qualifiers
- They are members of AFC - so their points are affected by the 0.86 confederation weighting. It used to be 0.85 - it will be marginally easier to gain points thanks to me :D
- AFC regional tournaments. Most of Australia's opponents play in some kind of regional championship (EAFF, WAFF, SAFF, ASEAN). With FIFA considering these games are friendlies, their ranking goes down and also Australia's ranking goes down.
- AFC is huge and temperature/humidity difference can play a role as Australia have recently seen against Oman.
- Australia's tendency of relaxing in dead-rubber games.
Japan made it to the last 16 of the 2010 FIFA World Cup and won the 2011 AFC Asian Cup. Their highest ranking after FIFA changed the rankings system in July 2006? 13th in April 2011.
I wrote in June 2011 a post about Australia clinching a seed at the 2010 World Cup. I said it would be extremely difficult. However, it was about peaking at a chosen time (October 2009), not maintaining it for a long time.
Good luck anyway!