BA is a business, they have to maximise their most profitable routes and it is not their fault that LHR is so popular.
If a third runway was to be built then I would guess that the regions would benefit. The first reaction would no doubt be for airlines flying to LHR to fill the slots with large planes to far flung destinations on ridiculous frequencies but over time slots will become available more easily.
All that is needed is either a third runway or a new London airport, but I cannot see any of that happening in the future, unless the Toff's policy on Heathrow turns out to be as lacklustre as his policy on the EU Treaty!
