Correct me if I'm wrong, but isn't indicated airspeed directly determined by the AoA which is directly controlled by the trim setting of the horizontal stabilizer and completely independent of engine power? So if I'm the pilot and I lose airspeed data in such conditions, I would assume I was already at a safe airspeed and AoA and not touch the trim, and then cut engine power to descend to a safer altitude. Of course, severe turbulence would cause temporary deviations from the equilibrium airspeed and AoA, but would a functional autopilot be able to correct these deviations faster than aircraft would by itself, thus reducing the possibility of a catastrophic deviation?
Now this is coming from a hang glider pilot with absolutely no experience in powered aircraft much less a 100 ton state-of-the-art transport so I may have no idea what I'm talking about.