I'm not sure you're right about BA, Trash. For some time there has been a school of thought within Waterworld that the best solution for BA is for LHR capacity to be permanently constrained, leading to an imbalance of supply and demand and the scope for BA to ration demand by price. The recent change in emphasis by WW might imply that this view is gaining currency within BA.
If R3 does go ahead, then 50% of the new slots will go to new entrants. Easyjet have made their views clear. The impact on the economics of BA's short haul operation, and its implications for the hub-spoke model, are pretty obvious. BA might seek to address this by shifting short haul to Vueling, but this would result in WW3 with the BA unions.