Well,
I think that one thing is to deploy 2 SA A/C in full business class configuration (32-50 seats) with a heavy schedule (as Privatair and BA - not aware of a similar AF operation), another is to buy 3 (three) A332 configured with 116 seats to do a daily return flight to LGW.
Future will say if this business will be sustainable. Personally I am pessimistic.
However, seen the deep pockets of the HNA group, I am convinced that this operation will stay alive for some time in any case
My 2 cents