My sister works with BA since 1996.
I can understand if BA wants to cut costs, especially at this time and mixed flying has also shown to be effective (most airlines also seem to do it). She came home from HKG the other day and that trip was probably worth at least £500. They have around 13 CC (not including the ICC) on each flight (three daily flights).
That's £6 500 per flight. £19 500 for all daily flights. £136 500 per week. And this is only for one destination!
Sorry to be a bit harsh. But, those numbers are fascinating and it does make sense if they want to introduce a new fleet with new T&C to cut costs.