The slots BA are using at LBA are surely to ensure they don't lose them at LHR ?
I may be wrong but suspect the services will rum for the foreeable future but will disappear if BA need a new far east or South American flight..
One other point, not sure what the fascination is with LHR. If you travel to Manchester you can hop on Qatar, Etihad or Emirates all offering ONE stop to Far Ear / Australia, crucially your flight WILL operate and you wont get dumped at LHR if its foggy or snowing !