Now that CX has at least 2 daily flights to LHR, they will test the water with one 77W with F. Most of the 77w with F had been mothballed or leased to other airlines. But they have the plane with F seats available if needed. However CX has to add a crew (scarce ressource) and get the logistics ready. Hopefully, they will get enough pax willing to pay the premium over J, rather than just awards.

The logistics might be more difficult for JFK where they are planning some irregular schedule with 8 flights per week (some day none, some day 2).