I suspect that this is one of "reduce-competition" benefit of the new revenue-sharing JV between BA and QR.
My guess is that QR will codeshare in Europe only on destinations where it does not fly and vice versa for BA. The fact that QR now used R class for most of its heavily-discounted fares makes it much less attractive to fly LHR-HKG on QR than was the case.
It might be a good business decision from BA viewpoint and it might allow to increase fares for LHR-based pax. But I doubt that QR carefully studied its implications. Most pax are not members of QR FFP and will never have enough business on QR to switch from another OW FFP. Many pax flying from Europe (exUK) to Asia are BAEC members. That will reduce the attraction for premium pax flying Europe-Asia.
Just as an example, my family (yes my children are business pax based in France or Asia) fly QR business some 10 return business tickets between Europe and Asia. We credit to BAEC and use the family account. That will be lost business for QR. We do not fly enough to have the luxury to maintain status without those flights. To me, moving to a much more expensive QR fare is not attractive compared to nonstop CX or other OW alternatives (yes, even BA with a transit in chaotic LHR).