I think this is gonna cause a lot of problems. I cannot imagine how noisy the flights will be with all the mobiles on. With 200-300 people on board you'll always have one mobile ringing during a flight. There ll be a lot of complainings and problems, esspecially in the premium cabins, where people are paying a lot of money to enjoy a sleep on a long haul.
Emirates'd rather offer internet connection such as Etihad.