Really depends on what Uncle Alan has in mind here. If his vision is to make Sydney be an international hub much like London or Dubai or Atlanta, then it might be an easy sell. Having lived in a number of continents, I'm surprised at how poorly connected Australia is in terms of flights. I mean 2 non-stop routes to Europe? Really?
You do know how far apart Australia and Europe are right...?
The two routes currently flown from PER (LHR daily, FCO seasonally) are #3 and #18 on the current longest routes flown worldwide. Moreover, Qantas is the
only airline that offers direct flights between Europe and Australia. There is not a single other provider. Why? Aviation technology has been limited in its capacity to carry people such long distances affordably. Having stopovers has been the only feasible method of getting from one end of the world to the other. The kangaroo route used to have many more stopovers too, so be thankful for those technological advances. Once Sunrise is up and running Qantas will occupy 8 of the top 8 longest commercial flights in the world with the various combinations of SYD and MEL to LHR, CDG, FRA, and JFK (yes, I know JFK isn't in Europe). Australia is just a long way from pretty much everywhere.
Of course there's way more flights to Asia and even the west coast of the US. SIN is busiest international route for each of SYD, MEL, BNE, PER, and ADL. That you've lived on a number of continents and are "surprised" by how poorly Australia is connected to Europe speaks more to the fact that maybe you just didn't realise how far away, and how small in terms of population, Australia is. Which is fine if you simply don't know, but assigning the lack of direct routes to Europe to any kind of unwillingness/stubbornness on behalf of Australia to be connected is frankly naive.
Sydney will never be a "hub" in the same what the London or Dubai are in terms of connecting international flights to further destinations - in 2019 it only just scraped into the top 50 busiest airports worldwide for total passenger traffic, and with a grand total of 3 million international passengers in FY2022 it's. The sole purpose will be getting Australians into, and out of Australia, directly from their desired destinations, and same for anybody wanting to visit the mythical land of Oz.
With all of that being said, and to get this back OT, a OW super-terminal would only make sense if there was an existing airport redevelopment going on and all of the OW airlines flying into SYD agreed that it would be a good idea. Qantas of course will be a driving factor as the largest user of the airport, but they wouldn't want to pay for it themselves. So to say "Qantas planning" might be a bit of a stretch, "Qantas lobbying for" might be more apt if/when the idea floats around again.
