I may be barking up the wrong tree here but are we not confusing a static situation with a dynamic one?
Practically, during a rapid transition from one airmass to another (assuming no change in wind velocity) TAS remains constant (inertia) while Mach and IAS change. If the change in temperature is more gradual, autothrottle/drag will keep Mach or IAS (whatever your reference is) constant while TAS changes... Yes?