I agree to an extent, but i reckon that a third team will eventually be on the cards, the big drawback is unlike Melbourne the third team will need its own stadium within its own demographic area.
That would mean another partnership with cricket perhaps.
Its a big stretch but the population and participation rates will eventually demand one.
Look I'm not immediately dismissing a 3rd syd team at some point, but on face value right now and all the forecasting it does seem unlikely. It's more likely and more viable anywhere else in the country bar syd and qld. That's just my opinion.