IMHO one consequence of BASSA's tactics will be that BASSA reps are no longer given time off from work to perform their union duties. They will be expected to do it on days off, as BA is legally entitled to insist.
So even if BASSA are allowed back in the building (which is not certain yet, I don't think), they just won't have time to get involved in day to day stuff like they used to.
I still think there's a fair chance BASSA will call an all out permanent strike from mid-April. If they do that, it's all over for them.