If it is indeed true that Boeing are considering a nitrogen generator installed on their #3 pack, it does sound like a good idea, but it had better be very very fool-proof.
Considering that the source of the Nitrogen is to be one of the A/C Packs, the 1 in 100,000 chance does exist that that pack may be the only operative pack, and extreme caution must be taken in the design process to ensure that the Nitrogen produced can never be supplied to the cabin.
Some years ago, NASA were purging a fuel cell with pure Nitrogen (normal procedure for many areas of industry), and several technicians entered the fuel cell unaware that the cell was still a Nitrogen rich environment. All died, very peacefully.
Regards,
Old Smokey