The number 1 ranking gets passed around between a few countries which suggests test cricket is highly competitive and/or everyone is too weak to have one team dominate. In terms of broadly competitive test cricket, there have been two eras of dominance by a single team - West Indies 1976-1995, Australia 1995-2005.30 years is a little different to a decade.
you can't compare afl to the wtc. during the afl cycle 'premiership season, everyone plays everyone.
the wtc doesn't allow everyone to play everyone during the championship cycle.
in any case i doubt an afl has won the flag but eluded to beat a team for 10 years.
not sure you can say the aussie team are average at the moment. sure the last 2 tests weren't great, but we were ranked #1 prior to that test series.
you could throw a blanket of 3-4 teams at the moment for the best test team - but average is harsh. even if australia are 4th best, thats still not 'average' - it's more a case of - not as per australia's lofty and high expectations.
India is probably the team most likely to attain that sort of dominance.