Exactly, BA need to be there! Take the subsidy and go, for Pete's sake. Look ahead and long term for once.
What evidence do you have that BA doesn't "look ahead and long term" ?
Even if we leave aside the well documented problems with UK visas for Chinese visitors, and the restrictions imposed by the China/UK bilateral, £30K subsidy per rotation isn't going to make much difference if the route isn't seen by BA as profitable in the short-term, and they would rather use the slots to fly somewhere more lucrative.