Dropping the minutiae of an accent color should not require a major rebranding project - just leave the yellow stripe off aircraft that go in for painting, and at the most, change the tail accent gold stripes to a light gray derived from adding a small amount of dark pigment to the white paint used on the rest of the aircraft.

Neither of these changes really require a rebranding project or an update to the brand beyond queueing up the update to supplemental materials due for re-ordering in the future, and updates to digital photo and video media. There should be little to no incremental cost approaching it this way vs the millions involved in a major rebranding effort with a new logo, typeface and color plan.