MB2002, I agree with you to some point that paper procedures do not extensively address Unreliable Airspeed at cruising level.
You keep mentioning Stall in your scenario. How/why a stall at cruising level? Unless someone is hiding behind a large newspaper, he will get cues that something is going on before...
Training lacks here: unless the speed/altitude (could be also TAT probes affected by ice particles impacting the A/THR...) discrepancy is obvious, we are very reluctant to disengage all automations.
There could be hundreds of different unreliable airspeed scenarii: if you're lucky, aircraft will go into ALTN law and disconnect everything for you...then if you apply pitch/thrust, you are SAFE (2.5° and 78% will work for any Airbus twin jet)
Past incidents have shown that those situations rarely exceed few minutes before everything goes back to normal...
If for any reason, you actually ended up in a stall with unreliable airspeeds...my question would be: how quickly can you determine what type of stall it is?...because correcting actions are not the same.