Long Haul daylight flights have always been a commercial problem , not just north -south /south- north, but east-west as well when an overnight option exists. The loss of a day severely affects the high yield business traffic, so they will almost invariably be less profitable than the overnights. However the cost of staying on the ground for 12 hours plus is also high and that is the counterbalancing calculation. So far though on S Africa- UK, and HKG , SIN, KUL and BKK to Europe the vast majority of schedules are still overnight although CX have now followed LH with a daylight ex HKG. TYO and SEL to Europe because of their shorter flight time have to be daylight and do well because there is no overnight alternative.
Gulf- Europe daylights do well because high yield Arab passengers generally prefer to avpid overnight travel.
BA have spasmodically tried Far East- London daylights ever since the Comets in the 60s but never with any great success,- possibly because they have never persevered long enough for the services to build their own markets.