It's sad to see SIN based crew go, but can understand the economics of maintaining a foreign based crew that drives this decision.

There is little "need" for Mandarin speakers when even SQ doesn't do announcements on the LHR and SYD routes in Mandarin.

On a recent flight I got chatting with one crew and found out that:
- SIN is the first to be closed because it has the weakest labour laws of all BA outposts.
- closure applies to both World Wide and Mixed Fleet crews.
- in theory one would argue that Mixed Fleet crews are already "cheap enough" and can be offered alternative base out of London to keep that staff employed, but BA is NOT assisting the staff to apply for UK work authorization. So unless that crew can prove right to work in the UK, this option is closed to them realistically.
- the staff haven't been told what the severance package is... but suspect for long serving World Wide staff this would be "sufficient but by no means generous" and for recently hired Mixed Fleet this is expected to be "pittance".