BA have vacated masses of office space at T5 to save money. An unintended consequence of this could be that HAL may say, “if you’re not going to rent this space from us, we’ll bring an airline in that will” and so BA will have to move a number of routes out of T5 to accommodate another airline.

HAL can’t do anything with all this office space they have after BA left as they’re not in the sort of location where you could place a shop or a lounge and the only airline in the building at present is British Airways.