You don't have to go to a gate to deplane and this is an extremely rare event. They'll just pull up a staircase and have them deplane to a shuttle eventually.

Most U.S. airports aren't equipped to deplane commercial airliners using stairs, especially at this scale.

You empty the planes at the gates and then push them back to parking (or park them on the runway if needed).

O’Hare is under construction. They’re building an entire new terminal and are operating with a lot less spare capacity while that happens.