One thing I am sure of, if there is a tram along George Street from Central to the Quay, the tram will be so overwhelmed with passengers, that new trams will have to be quickly ordered and the service interval reduced. Better that they initially order very big trams.
As an occasional visitor to Sydney, I have no idea about north south buses in the city. I either walk or use the underground train or sometimes the monorail. I won't live to be old enough to understand how buses in Sydney city work. But I know how trams work and if I see a track, I can see where the tram is going. I read that bus congestion is a problem in George Street. Nothing new there. Tram congestion used to be a problem in Sydney city. But they used to think laterally and do something about it.
One small step for mankind, the next step, a tram along Anzac Parade and Oxford Street and the eastern suburbs train line extended to Bondi Beach and then along the coast to Coogee. By running it along the coast, it will alleviate worries about the train pouring people into Bondi Beach. People will go on to other beaches. I feel sorry for locals who live at Bondi Beach and have to put up with the transfer from the train at Bondi Junction to a bus, among hordes of tourists.