I find this subject quite odd, IF it is true that these devices can have a dangerous effect on the operation of Aircraft then IMHO there is something very wrong with these Aircraft.
To blame mobile phones is just ridiculous, for many years I flew all over Australia in Aircraft that had a mobile phone fitted in the cockpit, ringer disabled in case it rang at a critical stage of flight, and more often than not all 3 of us in the cockpit would be using our mobile phones, NEVER any problems.
Admittedly these were REAL Aircraft, not FBW, but IF these FBW Aircraft are affected then the problem is with the Aircraft.
Having said that I would NOT want to be a passenger on a passenger flight with all these phones in use, NOT because of any risks but because it would be a nightmare.