My boss flew this flight CBR - SIN last night. Talking to him today he estimated there was only 70-80 pax in total on board. You would have to question how long that is sustainable once the subsidies run out.
December 2016 is presumably a busier month than March 2017 for passengers, although the latter means that the flights have had three more months to get known by prospective passengers, travel agents and online third party booking services. March 2017 is also not a school holiday month.
In that December, BITRE said that from Singapore to Canberra, there were 1775 inwards passengers who alighted there, while 2819 boarded in Canberra to travel to Singapore (or beyond.)
There were 968 inwards passengers from Wellington to Canberra and 1342 passengers who travelled from Canberra to Wellington on the outbound flight ex Oz.
It appears that in total 2743 used the Wellington - Canberra leg (which I believe includes those just travelling to Canberra, or going to Singapore or beyond) while from Canberra to Wellington total patronage appeared to be 4161.
I haven't looked up the days for December 2016 but I assume there were about 18 flights in each direction.
BITRE has yet to publish 2017 monthly figures.
SQ should stick with it for two or three years as barring a severe economic downturn, generally what occurs is as more travellers get to know about such flights, the numbers using them (subject to the fares being considered reasonable value) tend to rise.
Surely there must be plenty of public servants, diplomats, politicians and lobbyists who would find a CBR - WLG and return nonstop flight very, very useful. For residents of southern Sydney suburbs like Macarthur or Campbelltown, it could also be good, as it would be for residents of Yass, Cootamundra and even Wagga Wagga.
In the end, as well as bottoms on seats, yields are important. It is hard to imagine this route carrying much freight.