I just think that such routings are quite rare to find.
Same flt no. might be rare, but same aircraft is more common than you would think. After all, the incoming aircraft will have to be redployed to somewhere else. But it might not be to the same city everyday of the week.
I can see that there are many many other 6th freedom traffic, like SQ's Europe<->Australia.
On the same route, you also have major players like
CX,
TG,
MH and
EK.
Republic of Marshall Islands (Majuro<->Kwajalein) and Federated States of Micronesia (Truk<->Pohnpei<->Kosrae).
For small countries that can't support their own international airlines, it's not uncommon they "cede" their international rights to neighboring airlines. Then, I would personally treat those airlines as a native airline, in another word, those airlines represent multiple countries. If I understand correctly, for example, the US State Department actually represents Marshall Islands for all foreign-affair matters.
Also, what about SQ's plan to operate SYD-LAX? Is it going to be a stand alone service, or SIN-SYD-LAX? Where does that fit into all this?
Since there are more
SIN-
SYD flights than there would be
SYD-
LAX, then it can easliy be arranged as an extension of an existing flight, bit it doens't need to be same aircraft. So, it'll be fifth freedom. It's unlikely
SQ would operate as a stand-alone flight and venture into the realm of seventh freedom.