The fact of the matter is that there IS NO PROCEDURE for unreliable airspeed in the cruise.
Sorry but I think you got it wrong here...
The procedure on the 320 family says:
If the safe conduct of the flight is impacted :
-A/P and F/D off
-A/THR off
-Pitch thrust:
.Below Thrust Reduction altitude 15° Toga
.Above Thrust Reduction altitude 10° CLB.
.Above 10.000ft 5° CLB.
-Flaps Maintain.
-Speedbrake retract
-L/G up.
.When at or above MSA or circuit altitude level off for troubleshoot.
Therefore if it happens during cruise,
and safe conduct of the flight is impacted you have to go for 5° and CLB, then level off, and go for the pitch power data from the checklist.
If instead the safe conduct of the flight is not impacted (which was definitely not the case for the AF) the memory items can be skipped and the pitch power data used to maintain the level.
I am not accusing the AF pilots involved of not having used the proper procedure (too little details have been released at this moment especially on the intensity of the turbulence ), I am just saying that the procedure for unreliable speed is clearly there..
Speevy