If UNITE win this and the HK crew and by extension all crew from overseas bases gain the right to UK terms and conditions, there will remain little benefit for BA to keep them on. The risk being run is that is that BA will simply close the base and employ more UK based CC. More MF cabin crew.
As has already been said the industrial relations landscape has moved on since this case was started and is not directly related to the current dispute. However, the same UNITE that has been at the heart of the current dispute and has shown a stunning lack of strategic thinking is behind this too. Winning this is likely to have for more consequences than just allowing HK based crew to stay on to 60. This cannot be viewed in isolation, the reality is that the current state of affairs will impact upon the result of this case and vice versa.
The question at the crux of this is whether overseas employees of UK based companies are entitled to work under UK industrial relations laws. If they are then this ruling will have massive repercussions for UK industry and will cost the UK economy dearly.