My concern is how they are calculating maintenance costs of the copper tail. Telstra's linesmen are some of the few equipped/trained to maintain these lines, and in areas > 30 years old much of the copper is in poor condition or direct buried (read: $$$ to replace). Flooded pits causing comms connectivity issues, radio interference, etc all impact copper performance too.

Speed is often the argument for FTTN vs FTTH, when reliability should be.