The problem with holding the world cup is that by FIFA's regulations I don't believe that 'hills' are allowed? Stadiums must be all-seaters, and must have impecable facilities at top stadiums. Places like Lang Park, Telstra Stadium, and MCG are a start, but 32 teams are playing, so atleast 6+ venues are needed.
And although Australia did hold the olympics, the serious interest in the sport would be very little compared to other continents(all of them) so FIFA's best interests(purely financially) would rule us out. Also holding the WC means direct qualification, but we need to prove that we can get their first.