BA will not get the 400 they need by a long chalk.
Perhaps some of the CSD's will consider themselves 'management grades' thus entitled to do whatever they want, work whenever they want and not turn up whenever they want thus getting themselves thrown out without any 'derisory' payment? I do believe it's happened before eh Count?
Additional to the VR is the 90 day notice for redundancies (on the CC side) which could be implemented if no VR is taken. Whether or not this will be done on the flight crew side is yet to be seen but there has been no formal announcement of 90 days notice from flight ops yet.
Flight Ops can 'carry' the surplus if necessary, what remains to be seen is the 'cost' to the community of carrying that surplus on top of the concessions made for the integration of BMI. Nothing in life is free.