US air traffic growth and implications for airlines

Data has shown that GDP is the closest guide to air travel growth. Here is an example of the research.  ICAO also offers some valuable charts backing this up.

This is all great, but what happens as traffic growth continues?  There isn’t an airport with perpetual construction.  However, in almost every case, that construction is not adding runway capacity.  This is not unique to the United States.  The poster child for this problem is London Heathrow.  Airport capacity is a real issue at Heathrow and is increasing at other mega hubs.