According to BASSA, as posted a fair few pages ago, the number of crew expressing interest in VR was about 3600 in total. Take off about a third of that number and you have the number who would probably take it.
However, the rub lies in that there needs to be productivity agreements in place if the company is to take the extra expense of VR (the VR package would be above and beyond a CR package).
BASSA failed to agree by the deadline so the company withdrew its VR package proposals that were never even discussed.
If it comes to the headcount reduction of 2000 then, in realistic terms, that could be up to 4000 personnel depending upon part time etc. Those who volunteer to go will possibly get an enhanced package but there are no guarantees. CR is the cheapest way for the company to shed personnel.
SOSR has been used in many cases of industrial tribunal where new contracts have been issued with those not signing being deemed to have 'resigned' from their previous contract. If the company can realistically state that it would have struggled to stay in 'competitive business' if change hadn't occurred then SOSR places the burden of proof on the employee not the employer. Thus making it very difficult to get through tribunal. If BA makes CR decisions based upon a streamlined business model then the continued employment of 36000+ people verses the loss by CR of 2-3000 makes compelling business sense.