CX Golds (CX's middle tier) have op-up priority over EMs (per a thread posted last year here), and with the new 74A F capacity is down by three seats. I just flew F SFO-HKG a few days ago, it was the new F so there were 9 seats. Y was oversold but J soaked up the capacity except for one or two, F went out with 8/9 and I think two of those were op-ups, both of who were CX DMs.

Working against you are the reduced number of F seats (12 reduced to 9) if you get the new plane, Diamond and Gold priority over you, and lower J loads. Cross your fingers they REALLY overload J and also have a low load factor in F.

Before they changed the op-up priority, it was pretty standard on this board to see OW pax saying how they were thankful for the op-ups. I haven't seen to many of those lately, although it doesn't necessarily mean causality.

Regarding what you can do: Checking in early will help, because you'll get a lower boarding number. They go by that when ranking people of the same level, with the lower boarding number winning out with equally ranked pax (in your case you're non-CX EM, which is after CX Golds. Above you will be CX Golds and any form of CX Diamond).