Boeing should send a letter to the FAA recommending all of their aircraft that do not have inerting tanks be grounded ASAP
So, is all the engineering done and the retrofit kits ready to go? If not, Boeing's customers have a case for suing them for delaying the needed fix. Even if the fix is ready to go, putting your airline customers in that kind of position (even if it was their fault the fix was not implemented) isn't good for customer relations.