there are ways to handle these types of situations that don't involve talking to gate agents and standing in line. when you know your flight is going to be delayed or canceled immediately call the carrier, don't go wait in the line or talk to the agent. have another phone ready with available flights with any carrier, if they tell you that they don't work with that carrier (usually SW who works with nobody) tell them you will book it OOP and get confirmation they will reimburse you. then book the flight. while first class passengers from your current flight are just starting to be served and rebooked by the gate agent or at the help desk halfway across the airport you have your seat.
