The hearing is to decide whether the imposition of reduced cabin crew is contractual or not.
If BA lost and appealed, there is nothing to stop them imposing anything else they might like. They are not answerable to this court on IMPOSING changes to cabin crew working agreements, only on the specific case of cabin crew complements.
A more likely scenario is a 90 day notice to make the changes fully legal even if Bassa won the case.
(20% chance of that, IMHO)