For freight perhaps, but for commuters who actually live in Sydney proper (as opposed to the extreme outer most suburbs of greater Sydney) I think not. I've seen nothing about fast 24hr public transport to the new airport?
Given how built-up Sydney is, the only fast option would be a new underground subway tunnel for the whole way to get into Sydney proper for a business meeting/tourist hotel or home for anyone living north shore, east or inner west.
If I need to take the 6am SYD-MEL, when I leave home at 4:45am I can be in the lounge by 5:05am Barista coffee in hand having checked luggage. To make a 6am flight from the new airport would mean leaving home at like 3am if not earlier and $200+ on an uber/taxi as Sydney trains dont run 24*7, over night busses run about once an hour to the city.