We are in the realm of speculation, but... I've said this before and I wouldn't be surprised if BA implemented measures to ensure that GGL/CCR is attained by frequent flyers who actually fly BA a lot... The simple way of doing it is to have only TPs earned on BA count towards GGL qualification. In my view it would make commercial sense. It is easy to implement from an IT standpoint (even for BA...) and there is precedent in other airlines (see LH/LX where miles only flown in premium cabin on their airlines count towards HON-circle qualification, ie the "HON-circle miles").
There is then the whole argument of revenue-based FFPs, but I now don't see BA going in that direction...