ITS
What you said about QF code sharing is not quite accurate. QF will codeshare with another airline if they think the market is too small for a QF operated flight, but a market exists for reduced numbers.
Basically they codeshare on high risk routes, when someone else bears the risks of empty aircraft, high number of diversions, major cost blowout due to tech problems.
Basically codesharing allows them to sell their tickets through the QF travel group, with reduced risk to QF's bottom line.
You are accurate however when you say the route is not viable for a full aircraft dedicated to it.