When can we expect any of them to think about upgrading? In 12 years, none, not one, of the 57 class 1 airports I serve has so much as thought about upgrading to class 2. Palm Springs, for example, features 26 flights a day from 19 carriers, yet it remains a class 1 airport. The only option becomes to drop service as we move away from props to jets, and also leaves a -lot- of demand unserved in many cases.
Overall I think the airport infrastructure feature has been a success, but I do feel there should be a quicker move from class 1 to 2 to 3 to accommodate larger planes, or maybe a player initiated option where money can be invested in infrastructure, and maybe other airlines using said infrastructure have to pay fees to the airline owing the gates for x period of time if they fly there.
Just some thoughts....