It would be typically short sighted of them though.
The same geniuses that thought Clive Palmer and Nathan Tinkler were good ideas are behind putting a club in a non-footballing stronghold who's limited football fanbase is generally aligned to Sydney FC.
Cannibalisation won't grow the league it will just dilute the market you have.
Mind you this is also the geniuses who think the opposing teams in a derby match lining up facing each other isn't remotely contrived or embarrassing.
De Bohun needs to spend more time making this league viable and less time out on this piss until four in the morning.
If you are referring to Sutherland, you are seriously misinformed. The people of the Sutherland Shire (and a lot of Wollongong/Illawarra) would support Sutherland and Sydney FC would lose about one third of its fan base.
On this wider issue though, there is a natural untapped derby "market" of 1.2 million in Auckland. From a franchising perspective it sharks all over supposed other Aussie regional or even Sydney/Melbourne new entry markets. Hyundai as major sponsor would surely want Auckland in the mix too. League, basketball "Aussie" leagues have been trans Tasman leagues for years. Our primary rugby and netball competitions don't work without Kiwis and Aussies working together. As much as we love to hate each other, we desperately need each other. The posturing is getting ridiculous now and both key parties need to put an end to it quickly.
