Critical Lemon is correct. The only way any rivalry will work is if you have a geographic rivalry. If you just put another team into a city then how can that team compete when the other team has had all that extra time in the competition? It only sort of works in Melbourne because it is such a big city and had millions of NSL teams.
If you do want a geographic rivalry then they have to play in a different stadium. Neither Brisbane, Perth or Adelaide seem to have extra stadiums in distinct geographic locations. Therefore any new team coming in to the competition would have to play at the same stadium as the current team or else raise 40 million dollars. What council wants to spend that sort of money when they already have an A-League team? Most likely what would happen is the new team would just play at the same stadium as the old team, get low crowds but the FFA would get one completely manufactured derby 3 times a year. I would prefer to have a new team in a new location with genuine community support.
It's 22 kilometres from Pirtek Stadium to the SFS and some areas of Western Sydney are a lot further away.
It may be only 22km distance but actually they are hundreds of miles apart because western Sydney (say west of Parramatta) is a completely different mindset from the east of the "divide". You could make the same argument about drawing a horizontal line across greater Auckland. I have never lived in Auckland apart from very frequent visits but I lived in Sydney for 12 years and think it is a valid comparison.
You could perhaps argue that people from Manukau or Papakura should be able to support the same football team as people from Albany or Takapuna. That was a much tougher proposition In Sydney, separated by economic and ethnic dividing lines more pronounced than those in Auckland. The creation of WSW was a logical step championed by Frank Lowy. I think he was correct and we see that in the support WSW is getting, whether we like their supporters' antics or not.
I think you completely missed my point.
I was saying that the geographic distance in Sydney, coupled with an established football culture out west, coupled with 4 million people, coupled with a purpose build stadium, coupled with huge sponsorship dollars meant WSW would always be a success.
However, there is not the same geographic distance in Adelaide, West Adelaide does not have an established football culture, does not have the population and does not have their own stadium. Therefore West Adelaide will never be a success.