Only other option is to move to HKG as a Pax FO if the company deems there to be a place available. Another thread mentions that recently the company has said that no places are open at present.
My understanding is that if you have finished your freighter commitment AND have seniority to be a pax FO (ie no SOs senior to you), then you have a choice of either staying on your freighter scale on the base, or moving to HK as a pax FO.
In the past, they've stopped some people moving to the pax fleet on the basis that they need you on the freighter fleet, which they are allowed to do, however, in that case, those individuals have/should have been paid the difference (a bit like by-pass pay).
If you don't have the seniority to get a pax base, then you CANNOT drift across to the pax fleet on your base. Some people have tried (and possibly got away with it), but that is a blatant breach of contract.