Cathay Pacific Asia Miles - BA/CX splitting the pie

I used to fly TPE-HKG-FRA-Central Europe, including Vie, LNZ, Budapest, Prague. The CX fare through FRA was always the cheapest business class available. When I booked my ticket to VIE for 9/5 today, my travel agent told me that for certain destinations - including all the above, BA will now be cheaper in all classes. For other destinations, CX will compete more fiercely, e.g. LHR, and all the BA codeshare destinations. My travel agent thinks its kind of a deal BA and CX have to split the European pie. It used to be a EUR 1000 difference in favor of CX, now its the other way round. I guess I'll be seeing more of BA from now on.

This isn't new. Airlines have always been cooperating on routes/fares for ions.

Would you believe that there's even a fare shared by CX and SQ for flying out of London? Basically one can fly to/from Singapore via HKG.

And that's not even splitting the pie with the same alliance.