Currently, the plan appears to be have a 'jammer' that prevents the cellphone receiving a base station other than the pico cell. Some of us question how a jammer is going to jam the top 900MHz GSM channel and not the adjacent DME channel, but we do know Airbus don't think it a problem, although the German authorities are questioning all this.
As far as failure mode of the pico cell and the results are concerned, I don't believe that has been considered. This is very much an area where the 'telecom' people are only concerning themselves with the technicalities of the mobile 'phone communications, and are relying on the aircraft people such as ICAO, the aircraft manufacturers and so on to come up with the necessary immunity requirements and so forth to protect the aircraft systems.
I read somewhere a suggestion that airlines are looking to charge extra for aisle and window seats - maybe they'll be able to charge extra for having seats with no mobile phone service around them!