Got it, if I am flying in an aircraft with defective software and or an inoperative sensor(s) and decide to fly near stall speed at 40,000 feet this info will come in handy.

To the OP in this thread, the answer is still no change with altitude for all practical purposes, as far as light GA aircraft go.

Having flown a variety of swept wing military aircraft into and out of stalls at altitude many times, I will tell you from a practical standpoint that I never looked at the airspeed but flew the entry and exit based on buffet and performance. Ignorance on my part was bliss in this case.