If New Fleet comes in - you will be sitting at home anyway - better on a full-time contract than a part-time one. If WW Psrs do not transfer, there will be too many of them. They will be forced to rethink and either offer a better redundancy package, or use them to work down, up etc. But they will not be able to employ new crew, on new contracts with the current level of staff.
There's just the small issue of the HR1 BA filed for 2000 redundancies from IFCE. If people don't take VR or part time BA have ticked all the legal boxes necessary to sack 2000 crew and continue with the new crewing levels.