I would think the most realistic order would be:
Only for the departing flight. If you are arriving, the current one would be the "correct" order.
And no, there's a reason why we can't change the menu order depending if are you departing or arriving, and it's because some users (home cockpit builders, for example), have complex systems using programmed keyboard macros that rely on the GSX menu order to always be the same, and there are also some addons that interface with GSX that also expects the menu would always be in the same order.
