I made a similar point to dj6 offline the other day.
There is a fixation on hubs and networks as we know them.
But what if something came along that was a game-changer? EZY/FR getting into long-haul and connections in a big way? Smaller aircraft with long range coming on the market making LBA/SOU and any other regional airport inbetween non-stop to NYC plausible?
Then is an extra runway at LHR compared to LGW/STN so important?