I have very little understanding of this, so feel free to tell me I'm completely wrong, however.
What if CX isn't opening this route mainly for pax but rather for cargo? They have flown a lot of cargo flights for a long time, now by opening this route they can still carry it as hold-cargo, but they can also dip their toe into the pax-market and see what the demand looks like. If they can make money on the pax (as well as take some off their middle-east competition) then they will do so, but if not the cargo might be what keeps the route going.
Any thoughts on this reasoning?